Documentation: simplify refspec format description

The refspec format description was a mix of regexp and BNF, making it
very difficult to read. The format was also wrong: it did not show
that each part of a refspec is optional in different situations.

Rather than having a confusing grammar, just present the format in
informal prose.

Signed-off-by: Anders Melchiorsen <mail@cup.kalibalik.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-push.txt

@@ -33,10 +33,11 @@ OPTIONS
 	of a remote (see the section <<REMOTES,REMOTES>> below).
 
 <refspec>...::
-	The canonical format of a <refspec> parameter is
-	`+?<src>:<dst>`; that is, an optional plus `{plus}`, followed
-	by the source ref, followed by a colon `:`, followed by
-	the destination ref.
+	The format of a <refspec> parameter is an optional plus
+	`{plus}`, followed by the source ref <src>, followed
+	by a colon `:`, followed by the destination ref <dst>.
+	It is used to specify with what <src> object the <dst> ref
+	in the remote repository is to be updated.
 +
 The <src> side represents the source branch (or arbitrary
 "SHA1 expression", such as `master~4` (four parents before the

Documentation/pull-fetch-param.txt

@@ -5,15 +5,14 @@
 	of a remote (see the section <<REMOTES,REMOTES>> below).
 
 <refspec>::
-	The canonical format of a <refspec> parameter is
-	`+?<src>:<dst>`; that is, an optional plus `{plus}`, followed
-	by the source ref, followed by a colon `:`, followed by
-	the destination ref.
+	The format of a <refspec> parameter is an optional plus
+	`{plus}`, followed by the source ref <src>, followed
+	by a colon `:`, followed by the destination ref <dst>.
 +
 The remote ref that matches <src>
 is fetched, and if <dst> is not empty string, the local
 ref that matches it is fast forwarded using <src>.
-Again, if the optional plus `+` is used, the local ref
+If the optional plus `+` is used, the local ref
 is updated even if it does not result in a fast forward
 update.
 +