documentation: Moved "Git" section to the ref-manual

Fixes [YOCTO #11630]

The "Git" section in the dev-manual is really about concepts.
There are a couple of examples that might or not might be
allowed to ultimately stay.  I have moved the section to the
ref-manual.  If those examples get replicated in the new
dev-manual, I will update the "Git" section further.  For now,
however, these remain in this moved section.

(From yocto-docs rev: 2e4b87fdab29c13ce0d2314e50c93e37404b6f7e)

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

documentation/bsp-guide/bsp.xml

@@ -1144,7 +1144,7 @@
 
                 <para>
                     Designed to have a  command interface somewhat like
-                    <ulink url='&YOCTO_DOCS_DEV_URL;#git'>Git</ulink>, each
+                    <ulink url='&YOCTO_DOCS_REF_URL;#git'>Git</ulink>, each
                     tool is structured as a set of sub-commands under a
                     top-level command.
                     The top-level command (<filename>yocto-bsp</filename>