ls-files: clarify descriptions of status tags for -t

Much like the file selection options we tweaked in the last commit, the
status tags printed with -t had descriptions that were easy to
misunderstand, and for many of the same reasons.  Clarify them.

Also, while at it, remove the "semi-deprecated" comment for "git
ls-files -t".  The -t option was marked as semi-deprecated in 5bc0e24
("Document ls-files -t as semi-obsolete.", 2010-07-28) because:

    "git ls-files -t" is [...] badly documented, hence we point the
    users to superior alternatives.
    The feature is marked as "semi-obsolete" but not "scheduled for removal"
    since it's a plumbing command, scripts might use it, and Git testsuite
    already uses it to test the state of the index.

Marking it as obsolete because it was easily misunderstood, which I
think was primarily due to documentation problems, is one strategy, but
I think fixing the documentation is a better option.  Especially since
in the intervening time, "git ls-files -t" has become heavily used by
sparse-checkout users where the same confusion just doesn't apply.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

Documentation/git-ls-files.txt

@@ -137,25 +137,27 @@ OPTIONS
 	with `-s` or `-u` options does not make any sense.
 
 -t::
-	This feature is semi-deprecated. For scripting purpose,
-	linkgit:git-status[1] `--porcelain` and
+	Show status tags together with filenames.  Note that for
+	scripting purposes, linkgit:git-status[1] `--porcelain` and
 	linkgit:git-diff-files[1] `--name-status` are almost always
 	superior alternatives, and users should look at
 	linkgit:git-status[1] `--short` or linkgit:git-diff[1]
 	`--name-status` for more user-friendly alternatives.
 +
 --
-This option identifies the file status with the following tags (followed by
-a space) at the start of each line:
-
-	H::	cached
-	S::	skip-worktree
-	M::	unmerged
-	R::	removed/deleted
-	C::	modified/changed
-	K::	to be killed
-	?::	other
-	U::     resolve-undo
+This option provides a reason for showing each filename, in the form
+of a status tag (which is followed by a space and then the filename).
+The status tags are all single characters from the following list:
+
+	H::	tracked file that is not either unmerged or skip-worktree
+	S::	tracked file that is skip-worktree
+	M::	tracked file that is unmerged
+	R::	tracked file with unstaged removal/deletion
+	C::	tracked file with unstaged modification/change
+	K::	untracked paths which are part of file/directory conflicts
+		which prevent checking out tracked files
+	?::	untracked file
+	U::     file with resolve-undo information
 --
 
 -v::