Documentation: typofix --column description

f4ed0af6 (Merge branch 'nd/columns', 2012-05-03) brought in three
cut-and-pasted copies of malformatted descriptions.  Let's fix them
all the same way by marking the configuration variable names up as
monospace just like the command line option `--column` is typeset.

While we are at it, correct a missing space after the full stop that
ends the sentence.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-branch.txt

@@ -153,7 +153,7 @@ OPTIONS
 --column[=<options>]::
 --no-column::
 	Display branch listing in columns. See configuration variable
-	column.branch for option syntax.`--column` and `--no-column`
+	`column.branch` for option syntax. `--column` and `--no-column`
 	without options are equivalent to 'always' and 'never' respectively.
 +
 This option is only applicable in non-verbose mode.

Documentation/git-status.txt

@@ -130,7 +130,7 @@ ignored, then the directory is not shown, but all contents are shown.
 --column[=<options>]::
 --no-column::
 	Display untracked files in columns. See configuration variable
-	column.status for option syntax.`--column` and `--no-column`
+	`column.status` for option syntax. `--column` and `--no-column`
 	without options are equivalent to 'always' and 'never'
 	respectively.
 

Documentation/git-tag.txt

@@ -134,7 +134,7 @@ options for details.
 --column[=<options>]::
 --no-column::
 	Display tag listing in columns. See configuration variable
-	column.tag for option syntax.`--column` and `--no-column`
+	`column.tag` for option syntax. `--column` and `--no-column`
 	without options are equivalent to 'always' and 'never' respectively.
 +
 This option is only applicable when listing tags without annotation lines.