toaster-manual: Fixed external links

Found four links going to the dev-manual that should have benn going
to the ref-manual.  These were for YP terms.  Fixed them.

(From yocto-docs rev: 0c75eda3a772d8c40e381e44e563a5b79b3d0cb5)

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

documentation/toaster-manual/toaster-manual-intro.xml

@@ -7,7 +7,7 @@
 
     <para>
         Toaster is a web interface to the Yocto Project's
-        <ulink url='&YOCTO_DOCS_DEV_URL;#build-system-term'>OpenEmbedded build system</ulink>.
+        <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>.
         The interface enables you to configure and run your builds.
         Information about builds is collected and stored in a database.
         You can use Toaster to configure and start builds on multiple

documentation/toaster-manual/toaster-manual-reference.xml

@@ -677,7 +677,7 @@
             created that are specific to Toaster and are used to control
             configuration and back-end tasks.
             You can locate these commands in the
-            <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
+            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
             (e.g. <filename>poky</filename>) at
             <filename>bitbake/lib/manage.py</filename>.
             This section documents those commands.

documentation/toaster-manual/toaster-manual-setup-and-use.xml

@@ -18,7 +18,7 @@
 
         <para>
             Navigate to the root of your
-            <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
+            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
             (e.g. <filename>poky</filename>):
             <literallayout class='monospaced'>
      $ cd poky

documentation/toaster-manual/toaster-manual-start.xml

@@ -41,7 +41,7 @@
             The requirements file is located in the
             <filename>bitbake</filename> directory, which is located in the
             root directory of the
-            <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
+            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
             (e.g. <filename>poky/bitbake/toaster-requirements.txt</filename>).
             The dependencies appear in a <filename>pip</filename>,
             install-compatible format.