docs: move editorconfig.txt into plugins.txt

It helps to have plugins living in one common area, because it signals
to users the mechanisms for controlling them, which are typically driven
by keymaps and autocmds rather than builtin options.

We can always revisit if plugins.txt gets "too big" (for example, we may
want to introduce "project.txt" for the project concept, where
editorconfig and 'exrc' are relevant), but for now it's rather unusual
for editorconfig.txt to have its own dedicated helpfile.

Author: justinmk

runtime/doc/editorconfig.txt

@@ -11,19 +11,19 @@ Plugins and modules included with Nvim
 Nvim includes various Lua and Vim plugins or modules which may provide
 commands (such as :TOhtml) or modules that you can optionally require() or
 :packadd. The Lua ones are not part of the |lua-stdlib|, that is, they are not
-available from the global `vim` module namespace. Some of the plugins are by
-default loaded while others require a |:packadd| to be loaded.
+available from the global `vim` module namespace. Some of the plugins are
+loaded by default while others are not loaded until requested by |:packadd|.
 
 ==============================================================================
 Standard plugins ~
 						*standard-plugin-list*
-Help-link		Loaded	Short description
+Help-link		Loaded	Short description ~
 |package-cfilter|	No	Filtering quickfix/location list
 |package-justify|	No	Justify text
 |package-nohlsearch|	No	Automatically run :nohlsearch
 |package-termdebug|	No	Debug inside Nvim with gdb
 |matchit|		Yes	Extended |%| matching
-|editorconfig.txt|	Yes	Detect and internet editorconfig
+|editorconfig|		Yes	Detect and internet editorconfig
 |spellfile.vim|		Yes	Install spellfile if missing
 |pi_tutor.txt|		Yes	Interactive tutorial
 |pi_gzip.txt|		Yes	Reading and writing compressed files
@@ -37,6 +37,91 @@ Help-link		Loaded	Short description
     |pi_spec.txt|	Yes	Filetype plugin to work with rpm spec files
 |tohtml|		Yes	Convert buffer to html, syntax included
 
+==============================================================================
+Builtin plugin: editorconfig                                    *editorconfig*
+
+Nvim supports EditorConfig. When a file is opened, after running |ftplugin|s
+and |FileType| autocommands, Nvim searches all parent directories of that file
+for ".editorconfig" files, parses them, and applies any properties that match
+the opened file. Think of it like 'modeline' for an entire (recursive)
+directory. For more information see https://editorconfig.org/.
+
+                                               *g:editorconfig* *b:editorconfig*
+
+EditorConfig is enabled by default. To disable it, add to your config: >lua
+    vim.g.editorconfig = false
+<
+
+(Vimscript: `let g:editorconfig = v:false`). It can also be disabled
+per-buffer by setting the |b:editorconfig| buffer-local variable to `false`.
+
+Nvim stores the applied properties in |b:editorconfig| if it is not `false`.
+
+                                              *editorconfig-custom-properties*
+
+New properties can be added by adding a new entry to the "properties" table.
+The table key is a property name and the value is a callback function which
+accepts the number of the buffer to be modified, the value of the property in
+the `.editorconfig` file, and (optionally) a table containing all of the other
+properties and their values (useful for properties which depend on other
+properties). The value is always a string and must be coerced if necessary.
+Example: >lua
+
+    require('editorconfig').properties.foo = function(bufnr, val, opts)
+      if opts.charset and opts.charset ~= "utf-8" then
+        error("foo can only be set when charset is utf-8", 0)
+      end
+      vim.b[bufnr].foo = val
+    end
+<
+
+                                                     *editorconfig-properties*
+
+The following properties are supported by default:
+
+
+charset                                                 *editorconfig.charset*
+    One of `"utf-8"`, `"utf-8-bom"`, `"latin1"`, `"utf-16be"`, or
+    `"utf-16le"`. Sets the 'fileencoding' and 'bomb' options.
+
+end_of_line                                         *editorconfig.end_of_line*
+    One of `"lf"`, `"crlf"`, or `"cr"`. These correspond to setting
+    'fileformat' to "unix", "dos", or "mac", respectively.
+
+indent_size                                         *editorconfig.indent_size*
+    A number indicating the size of a single indent. Alternatively, use the
+    value "tab" to use the value of the tab_width property. Sets the
+    'shiftwidth' and 'softtabstop' options. If this value is not "tab" and the
+    tab_width property is not set, 'tabstop' is also set to this value.
+
+indent_style                                       *editorconfig.indent_style*
+    One of `"tab"` or `"space"`. Sets the 'expandtab' option.
+
+insert_final_newline                       *editorconfig.insert_final_newline*
+    `"true"` or `"false"` to ensure the file always has a trailing newline as
+    its last byte. Sets the 'fixendofline' and 'endofline' options.
+
+max_line_length                                 *editorconfig.max_line_length*
+    A number indicating the maximum length of a single line. Sets the
+    'textwidth' option.
+
+root                                                       *editorconfig.root*
+    If "true", then stop searching for `.editorconfig` files in parent
+    directories. This property must be at the top-level of the `.editorconfig`
+    file (i.e. it must not be within a glob section).
+
+spelling_language                             *editorconfig.spelling_language*
+    A code of the format ss or ss-TT, where ss is an ISO 639 language code and
+    TT is an ISO 3166 territory identifier. Sets the 'spelllang' option.
+
+tab_width                                             *editorconfig.tab_width*
+    The display size of a single tab character. Sets the 'tabstop' option.
+
+trim_trailing_whitespace               *editorconfig.trim_trailing_whitespace*
+    When `"true"`, trailing whitespace is automatically removed when the
+    buffer is written.
+
+
 ==============================================================================
 Builtin plugin: tohtml                                                *tohtml*
 

runtime/doc/plugins.txt

@@ -89,10 +89,11 @@ local new_layout = {
 
 -- Map of new:old pages, to redirect renamed pages.
 local redirects = {
+  ['api-ui-events'] = 'ui',
   ['credits'] = 'backers',
+  ['plugins'] = 'editorconfig',
   ['terminal'] = 'nvim_terminal_emulator',
   ['tui'] = 'term',
-  ['api-ui-events'] = 'ui',
 }
 
 -- TODO: These known invalid |links| require an update to the relevant docs.

src/gen/gen_help_html.lua

@@ -384,25 +384,6 @@ local config = {
       return 'treesitter-' .. name:lower()
     end,
   },
-  editorconfig = {
-    filename = 'editorconfig.txt',
-    files = {
-      'runtime/lua/editorconfig.lua',
-    },
-    section_order = {
-      'editorconfig.lua',
-    },
-    section_fmt = function(_name)
-      return 'EditorConfig integration'
-    end,
-    helptag_fmt = function(name)
-      return name:lower()
-    end,
-    fn_xform = function(fun)
-      fun.table = true
-      fun.name = vim.split(fun.name, '.', { plain = true })[2]
-    end,
-  },
   health = {
     filename = 'health.txt',
     files = {
@@ -432,11 +413,20 @@ local config = {
   plugins = {
     filename = 'plugins.txt',
     section_order = {
+      'editorconfig.lua',
       'tohtml.lua',
     },
     files = {
+      'runtime/lua/editorconfig.lua',
       'runtime/lua/tohtml.lua',
     },
+    fn_xform = function(fun)
+      if fun.module == 'editorconfig' then
+        -- Example: "editorconfig.properties.root()" => "editorconfig.root"
+        fun.table = true
+        fun.name = vim.split(fun.name, '.', { plain = true })[2] or fun.name
+      end
+    end,
     section_fmt = function(name)
       return 'Builtin plugin: ' .. name:lower()
     end,