clRetainmemObject (1.2): remove extra ', and'

The note about implicit retains has an extra ', and' inherited from
the 1.1 man page (which listed clCreateImage2D and clCreateImage3D).

Fixes GitHub issue #15.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
diff --git a/sdk/1.2/docs/man/clRetainMemObject.xml b/sdk/1.2/docs/man/clRetainMemObject.xml
index e5f0022..8d61c9e 100644
--- a/sdk/1.2/docs/man/clRetainMemObject.xml
+++ b/sdk/1.2/docs/man/clRetainMemObject.xml
@@ -76,7 +76,8 @@
         <para>
             <citerefentry><refentrytitle>clCreateBuffer</refentrytitle></citerefentry>,
             <citerefentry><refentrytitle>clCreateSubBuffer</refentrytitle></citerefentry>, and
-            <citerefentry><refentrytitle>clCreateImage</refentrytitle></citerefentry>, and  perform an implicit retain.
+	    <citerefentry><refentrytitle>clCreateImage</refentrytitle></citerefentry>
+	    perform an implicit retain.
         </para>
 
         <para>