git-status.txt: describe --porcelain=v2 format

Update status manpage to include information about
porcelain v2 format.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-status.txt

@@ -183,12 +183,12 @@ in which case `XY` are `!!`.
 
 If -b is used the short-format status is preceded by a line
 
-## branchname tracking info
+    ## branchname tracking info
 
-Porcelain Format
-~~~~~~~~~~~~~~~~
+Porcelain Format Version 1
+~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The porcelain format is similar to the short format, but is guaranteed
+Version 1 porcelain format is similar to the short format, but is guaranteed
 not to change in a backwards-incompatible way between Git versions or
 based on user configuration. This makes it ideal for parsing by scripts.
 The description of the short format above also describes the porcelain
@@ -210,6 +210,124 @@ field from the first filename).  Third, filenames containing special
 characters are not specially formatted; no quoting or
 backslash-escaping is performed.
 
+Porcelain Format Version 2
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Version 2 format adds more detailed information about the state of
+the worktree and changed items.  Version 2 also defines an extensible
+set of easy to parse optional headers.
+
+Header lines start with "#" and are added in response to specific
+command line arguments.  Parsers should ignore headers they
+don't recognize.
+
+### Branch Headers
+
+If `--branch` is given, a series of header lines are printed with
+information about the current branch.
+
+    Line                                     Notes
+    ------------------------------------------------------------
+    # branch.oid <commit> | (initial)        Current commit.
+    # branch.head <branch> | (detached)      Current branch.
+    # branch.upstream <upstream_branch>      If upstream is set.
+    # branch.ab +<ahead> -<behind>           If upstream is set and
+					     the commit is present.
+    ------------------------------------------------------------
+
+### Changed Tracked Entries
+
+Following the headers, a series of lines are printed for tracked
+entries.  One of three different line formats may be used to describe
+an entry depending on the type of change.  Tracked entries are printed
+in an undefined order; parsers should allow for a mixture of the 3
+line types in any order.
+
+Ordinary changed entries have the following format:
+
+    1 <XY> <sub> <mH> <mI> <mW> <hH> <hI> <path>
+
+Renamed or copied entries have the following format:
+
+    2 <XY> <sub> <mH> <mI> <mW> <hH> <hI> <X><score> <path><sep><origPath>
+
+    Field       Meaning
+    --------------------------------------------------------
+    <XY>        A 2 character field containing the staged and
+		unstaged XY values described in the short format,
+		with unchanged indicated by a "." rather than
+		a space.
+    <sub>       A 4 character field describing the submodule state.
+		"N..." when the entry is not a submodule.
+		"S<c><m><u>" when the entry is a submodule.
+		<c> is "C" if the commit changed; otherwise ".".
+		<m> is "M" if it has tracked changes; otherwise ".".
+		<u> is "U" if there are untracked changes; otherwise ".".
+    <mH>        The octal file mode in HEAD.
+    <mI>        The octal file mode in the index.
+    <mW>        The octal file mode in the worktree.
+    <hH>        The object name in HEAD.
+    <hI>        The object name in the index.
+    <X><score>  The rename or copy score (denoting the percentage
+		of similarity between the source and target of the
+		move or copy). For example "R100" or "C75".
+    <path>      The pathname.  In a renamed/copied entry, this
+		is the path in the index and in the working tree.
+    <sep>       When the `-z` option is used, the 2 pathnames are separated
+		with a NUL (ASCII 0x00) byte; otherwise, a tab (ASCII 0x09)
+		byte separates them.
+    <origPath>  The pathname in the commit at HEAD.  This is only
+		present in a renamed/copied entry, and tells
+		where the renamed/copied contents came from.
+    --------------------------------------------------------
+
+Unmerged entries have the following format; the first character is
+a "u" to distinguish from ordinary changed entries.
+
+    u <xy> <sub> <m1> <m2> <m3> <mW> <h1> <h2> <h3> <path>
+
+    Field       Meaning
+    --------------------------------------------------------
+    <XY>        A 2 character field describing the conflict type
+		as described in the short format.
+    <sub>       A 4 character field describing the submodule state
+		as described above.
+    <m1>        The octal file mode in stage 1.
+    <m2>        The octal file mode in stage 2.
+    <m3>        The octal file mode in stage 3.
+    <mW>        The octal file mode in the worktree.
+    <h1>        The object name in stage 1.
+    <h2>        The object name in stage 2.
+    <h3>        The object name in stage 3.
+    <path>      The pathname.
+    --------------------------------------------------------
+
+### Other Items
+
+Following the tracked entries (and if requested), a series of
+lines will be printed for untracked and then ignored items
+found in the worktree.
+
+Untracked items have the following format:
+
+    ? <path>
+
+Ignored items have the following format:
+
+    ! <path>
+
+### Pathname Format Notes and -z
+
+When the `-z` option is given, pathnames are printed as is and
+without any quoting and lines are terminated with a NUL (ASCII 0x00)
+byte.
+
+Otherwise, all pathnames will be "C-quoted" if they contain any tab,
+linefeed, double quote, or backslash characters. In C-quoting, these
+characters will be replaced with the corresponding C-style escape
+sequences and the resulting pathname will be double quoted.
+
+
 CONFIGURATION
 -------------