overview-manual, dev-manual: Cleaned up links to source repos

I was using the "/cgit/cgit.cgi/" string as part of the link to
the source repos, which uses the ENTITY "&YOCTO_GIT_URL;".  That
ENTITY is all that is necessary to get the link to work.  I removed
the other stuff.

(From yocto-docs rev: f9a63c2cc824ef05230f614e933d178469890e97)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/dev-manual/dev-manual-common-tasks.xml

@@ -7425,7 +7425,7 @@ Some notes from Cal:
                 more secure.
                 You can find these tools in the
                 <filename>meta-security</filename> layer of the
-                <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'>Yocto Project Source Repositories</ulink>.
+                <ulink url='&YOCTO_GIT_URL;'>Yocto Project Source Repositories</ulink>.
             </para>
         </section>
     </section>

documentation/overview-manual/overview-manual-development-environment.xml

@@ -255,7 +255,7 @@
         <itemizedlist>
             <listitem><para id='source-repositories'>
                 <emphasis>
-                <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'>Source Repositories:</ulink>
+                <ulink url='&YOCTO_GIT_URL;'>Source Repositories:</ulink>
                 </emphasis>
                 This area contains IDE Plugins, Matchbox, Poky, Poky Support,
                 Tools, Yocto Linux Kernel, and Yocto Metadata Layers.

documentation/overview-manual/overview-manual-yp-intro.xml

@@ -779,7 +779,7 @@
                         in constrained environments.</para>
 
                         <para>You can find the Matchbox source in its
-                        <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'>repository</ulink>
+                        <ulink url='&YOCTO_GIT_URL;'>repository</ulink>
                         listed in the Yocto Project Source Repositories.
                         </para></listitem>
                     <listitem><para>