Fix some inconsistencies in the docs

Signed-off-by: Fredrik Kuivinen <freku045@student.liu.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-grep.txt

@@ -3,7 +3,7 @@ git-grep(1)
 
 NAME
 ----
-git-grep - print lines matching a pattern
+git-grep - Print lines matching a pattern
 
 
 SYNOPSIS

Documentation/git-mv.txt

@@ -3,7 +3,7 @@ git-mv(1)
 
 NAME
 ----
-git-mv - Script used to move or rename a file, directory or symlink.
+git-mv - Move or rename a file, directory or symlink.
 
 
 SYNOPSIS

Documentation/git-tag.txt

@@ -3,7 +3,7 @@ git-tag(1)
 
 NAME
 ----
-git-tag -  Create a tag object signed with GPG
+git-tag - Create a tag object signed with GPG
 
 
 SYNOPSIS