Merge branch 'bc/author-committer-doc' into maint

Clarify documentation on committer/author identities.

* bc/author-committer-doc:
  doc: provide guidance on user.name format
  docs: expand on possible and recommended user config options
  doc: move author and committer information to git-commit(1)

Documentation/config/user.txt

@@ -13,7 +13,12 @@ committer.email::
 	Also, all of these can be overridden by the `GIT_AUTHOR_NAME`,
 	`GIT_AUTHOR_EMAIL`, `GIT_COMMITTER_NAME`,
 	`GIT_COMMITTER_EMAIL` and `EMAIL` environment variables.
-	See linkgit:git-commit-tree[1] for more information.
++
+Note that the `name` forms of these variables conventionally refer to
+some form of a personal name.  See linkgit:git-commit[1] and the
+environment variables section of linkgit:git[1] for more information on
+these settings and the `credential.username` option if you're looking
+for authentication credentials instead.
 
 user.useConfigOnly::
 	Instruct Git to avoid trying to guess defaults for `user.email`

Documentation/git-commit-tree.txt

@@ -69,7 +69,6 @@ OPTIONS
 	Do not GPG-sign commit, to countermand a `--gpg-sign` option
 	given earlier on the command line.
 
-
 Commit Information
 ------------------
 
@@ -79,26 +78,6 @@ A commit encapsulates:
 - author name, email and date
 - committer name and email and the commit time.
 
-While parent object ids are provided on the command line, author and
-committer information is taken from the following environment variables,
-if set:
-
-	GIT_AUTHOR_NAME
-	GIT_AUTHOR_EMAIL
-	GIT_AUTHOR_DATE
-	GIT_COMMITTER_NAME
-	GIT_COMMITTER_EMAIL
-	GIT_COMMITTER_DATE
-
-(nb "<", ">" and "\n"s are stripped)
-
-In case (some of) these environment variables are not set, the information
-is taken from the configuration items user.name and user.email, or, if not
-present, the environment variable EMAIL, or, if that is not set,
-system user name and the hostname used for outgoing mail (taken
-from `/etc/mailname` and falling back to the fully qualified hostname when
-that file does not exist).
-
 A commit comment is read from stdin. If a changelog
 entry is not provided via "<" redirection, 'git commit-tree' will just wait
 for one to be entered and terminated with ^D.
@@ -117,6 +96,7 @@ FILES
 SEE ALSO
 --------
 linkgit:git-write-tree[1]
+linkgit:git-commit[1]
 
 GIT
 ---

Documentation/git-commit.txt

@@ -367,9 +367,6 @@ changes to tracked files.
 +
 For more details, see the 'pathspec' entry in linkgit:gitglossary[7].
 
-:git-commit: 1
-include::date-formats.txt[]
-
 EXAMPLES
 --------
 When recording your own work, the contents of modified files in
@@ -463,6 +460,43 @@ alter the order the changes are committed, because the merge
 should be recorded as a single commit.  In fact, the command
 refuses to run when given pathnames (but see `-i` option).
 
+COMMIT INFORMATION
+------------------
+
+Author and committer information is taken from the following environment
+variables, if set:
+
+	GIT_AUTHOR_NAME
+	GIT_AUTHOR_EMAIL
+	GIT_AUTHOR_DATE
+	GIT_COMMITTER_NAME
+	GIT_COMMITTER_EMAIL
+	GIT_COMMITTER_DATE
+
+(nb "<", ">" and "\n"s are stripped)
+
+The author and committer names are by convention some form of a personal name
+(that is, the name by which other humans refer to you), although Git does not
+enforce or require any particular form. Arbitrary Unicode may be used, subject
+to the constraints listed above. This name has no effect on authentication; for
+that, see the `credential.username` variable in linkgit:git-config[1].
+
+In case (some of) these environment variables are not set, the information
+is taken from the configuration items `user.name` and `user.email`, or, if not
+present, the environment variable EMAIL, or, if that is not set,
+system user name and the hostname used for outgoing mail (taken
+from `/etc/mailname` and falling back to the fully qualified hostname when
+that file does not exist).
+
+The `author.name` and `committer.name` and their corresponding email options
+override `user.name` and `user.email` if set and are overridden themselves by
+the environment variables.
+
+The typical usage is to set just the `user.name` and `user.email` variables;
+the other options are provided for more complex use cases.
+
+:git-commit: 1
+include::date-formats.txt[]
 
 DISCUSSION
 ----------

Documentation/git.txt

@@ -482,13 +482,36 @@ double-quotes and respecting backslash escapes. E.g., the value
 Git Commits
 ~~~~~~~~~~~
 `GIT_AUTHOR_NAME`::
+	The human-readable name used in the author identity when creating commit or
+	tag objects, or when writing reflogs. Overrides the `user.name` and
+	`author.name` configuration settings.
+
 `GIT_AUTHOR_EMAIL`::
+	The email address used in the author identity when creating commit or
+	tag objects, or when writing reflogs. Overrides the `user.email` and
+	`author.email` configuration settings.
+
 `GIT_AUTHOR_DATE`::
+	The date used for the author identity when creating commit or tag objects, or
+	when writing reflogs. See linkgit:git-commit[1] for valid formats.
+
 `GIT_COMMITTER_NAME`::
+	The human-readable name used in the committer identity when creating commit or
+	tag objects, or when writing reflogs. Overrides the `user.name` and
+	`committer.name` configuration settings.
+
 `GIT_COMMITTER_EMAIL`::
+	The email address used in the author identity when creating commit or
+	tag objects, or when writing reflogs. Overrides the `user.email` and
+	`committer.email` configuration settings.
+
 `GIT_COMMITTER_DATE`::
-'EMAIL'::
+	The date used for the committer identity when creating commit or tag objects, or
-	see linkgit:git-commit-tree[1]
+	when writing reflogs. See linkgit:git-commit[1] for valid formats.
+
+`EMAIL`::
+	The email address used in the author and committer identities if no other
+	relevant environment variable or configuration setting has been set.
 
 Git Diffs
 ~~~~~~~~~