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

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

third_party/git/Documentation/line-range-format.txt

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+<start> and <end> can take one of these forms:
+
+- number
++
+If <start> or <end> is a number, it specifies an
+absolute line number (lines count from 1).
++
+
+- /regex/
++
+This form will use the first line matching the given
+POSIX regex. If <start> is a regex, it will search from the end of
+the previous `-L` range, if any, otherwise from the start of file.
+If <start> is ``^/regex/'', it will search from the start of file.
+If <end> is a regex, it will search
+starting at the line given by <start>.
++
+
+- +offset or -offset
++
+This is only valid for <end> and will specify a number
+of lines before or after the line given by <start>.
+
++
+If ``:<funcname>'' is given in place of <start> and <end>, it is a
+regular expression that denotes the range from the first funcname line
+that matches <funcname>, up to the next funcname line. ``:<funcname>''
+searches from the end of the previous `-L` range, if any, otherwise
+from the start of file. ``^:<funcname>'' searches from the start of
+file.