Merge branch 'jc/doc-boolean-synonyms' into next

Doc updates.

* jc/doc-boolean-synonyms:
  doc: centrally document various ways tospell `true` and `false`

Author: gitster

Documentation/git-config.adoc

@@ -213,7 +213,9 @@ See also <<FILES>>.
 +
 Valid `<type>`'s include:
 +
-- 'bool': canonicalize values as either "true" or "false".
+- 'bool': canonicalize values `true`, `yes`,`on`, and positive
+  numbers as "true", and values `false`, `no`, `off` and `0` as
+  "false".
 - 'int': canonicalize values as simple decimal numbers. An optional suffix of
   'k', 'm', or 'g' will cause the value to be multiplied by 1024, 1048576, or
   1073741824 upon input.

Documentation/git.adoc

@@ -472,8 +472,9 @@ Environment Variables
 ---------------------
 Various Git commands pay attention to environment variables and change
 their behavior.  The environment variables marked as "Boolean" take
-their values the same way as Boolean valued configuration variables, e.g.
-"true", "yes", "on" and positive numbers are taken as "yes".
+their values the same way as Boolean valued configuration variables, i.e.,
+"true", "yes", "on" and positive numbers are taken as "yes", while "false",
+"no", "off", and "0" are taken as "no".
 
 Here are the variables:
 

Documentation/pretty-formats.adoc

@@ -339,10 +339,10 @@ insert an empty string unless we are traversing reflog entries (e.g., by
 decoration format if `--decorate` was not already provided on the command
 line.
 
-The boolean options accept an optional value `[=<bool-value>]`. The values
-`true`, `false`, `on`, `off` etc. are all accepted. See the "boolean"
-sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
-option is given with no value, it's enabled.
+The boolean options accept an optional value `[=<bool-value>]`. The
+values taken by `--type=bool` git-config[1], like `yes` and `off`,
+are all accepted.  Giving a boolean option without `=<value>` is
+equivalent to giving it with `=true`.
 
 If you add a `+` (plus sign) after '%' of a placeholder, a line-feed
 is inserted immediately before the expansion if and only if the