urls.txt: document optional port specification in git URLS

Signed-off-by: NStefan Naewe <stefan.naewe+git@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/urls.txt

@@ -6,10 +6,10 @@ to name the remote repository:
 
 ===============================================================
 - rsync://host.xz/path/to/repo.git/
-- http://host.xz/path/to/repo.git/
-- https://host.xz/path/to/repo.git/
-- git://host.xz/path/to/repo.git/
-- git://host.xz/~user/path/to/repo.git/
+- http://host.xz{startsb}:port{endsb}/path/to/repo.git/
+- https://host.xz{startsb}:port{endsb}/path/to/repo.git/
+- git://host.xz{startsb}:port{endsb}/path/to/repo.git/
+- git://host.xz{startsb}:port{endsb}/~user/path/to/repo.git/
 - ssh://{startsb}user@{endsb}host.xz{startsb}:port{endsb}/path/to/repo.git/
 - ssh://{startsb}user@{endsb}host.xz/path/to/repo.git/
 - ssh://{startsb}user@{endsb}host.xz/~user/path/to/repo.git/