feat(man): respect 'wrapmargin' when wrapping man pages (neovim#24091)

Author: gpanders

runtime/doc/news.txt

@@ -134,6 +134,8 @@ The following changes to existing APIs or features add new behavior.
 • |:checkhealth| buffer now implements |folding|. The initial folding status is
   defined by the 'foldenable' option.
 
+• |:Man| now respects 'wrapmargin'
+
 ==============================================================================
 REMOVED FEATURES                                                 *news-removed*
 

runtime/lua/man.lua

@@ -436,7 +436,7 @@ local function get_page(path, silent)
   elseif vim.env.MANWIDTH then
     manwidth = vim.env.MANWIDTH
   else
-    manwidth = api.nvim_win_get_width(0)
+    manwidth = api.nvim_win_get_width(0) - vim.o.wrapmargin
   end
 
   local cmd = localfile_arg and { 'man', '-l', path } or { 'man', path }