merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/Documentation/gitrevisions.txt

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+gitrevisions(7)
+===============
+
+NAME
+----
+gitrevisions - Specifying revisions and ranges for Git
+
+SYNOPSIS
+--------
+gitrevisions
+
+
+DESCRIPTION
+-----------
+
+Many Git commands take revision parameters as arguments. Depending on
+the command, they denote a specific commit or, for commands which
+walk the revision graph (such as linkgit:git-log[1]), all commits which are
+reachable from that commit. For commands that walk the revision graph one can
+also specify a range of revisions explicitly.
+
+In addition, some Git commands (such as linkgit:git-show[1] and
+linkgit:git-push[1]) can also take revision parameters which denote
+other objects than commits, e.g. blobs ("files") or trees
+("directories of files").
+
+include::revisions.txt[]
+
+
+SEE ALSO
+--------
+linkgit:git-rev-parse[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite