gitattributes: Document built in hunk header patterns

Since the hunk header pattern text was written patterns for Ruby and
Pascal/Delphi have been added.  For users to be able to find them they
should be documented not only in code.

Signed-off-by: Gustaf Hendeby <hendeby@isy.liu.se>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: hendeby

Documentation/gitattributes.txt

@@ -307,9 +307,16 @@ backslash, and zero or more occurrences of `sub` followed by
 There are a few built-in patterns to make this easier, and `tex`
 is one of them, so you do not have to write the above in your
 configuration file (you still need to enable this with the
-attribute mechanism, via `.gitattributes`).  Another built-in
-pattern is defined for `java` that defines a pattern suitable
-for program text in Java language.
+attribute mechanism, via `.gitattributes`).  The following built in
+patterns are available:
+
+- `java` suitable for source code in the Java lanugage.
+
+- `pascal` suitable for source code in the Pascal/Delphi language.
+
+- `ruby` suitable for source code in the Ruby language.
+
+- `tex` suitable for source code for LaTeX documents.
 
 
 Performing a three-way merge