documentation: Fixed links for "build-directory" term.

Fixes [YOCTO #11630]

Moving the "Yocto Project Terms" section from the dev-manual to the
ref-manual broke several links to the id "build-directory".  I fixed
these to reference into the ref-manual now.

(From yocto-docs rev: debe2ae8ce203ebe0f1cee0de54124c15df8bb7e)

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

documentation/ref-manual/faq.xml

@@ -702,7 +702,8 @@
                 <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
                 or
                 <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>).
-                By default, this <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
+                By default, this
+                <link linkend='build-directory'>Build Directory</link>
                 is named <filename>build</filename> but can be named
                 anything you want.
             </para>
@@ -765,7 +766,7 @@
 
             <para>
                 Meanwhile, <filename>DESTDIR</filename> is a path within the
-                <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
+                <link linkend='build-directory'>Build Directory</link>.
                 However, when the recipe builds a native program (i.e. one
                 that is intended to run on the build machine), that program
                 is never installed directly to the build machine's root