sphinx: replace bitbake labels with references to corresponding title

In order to remove autogenerated labels in the bibtake docs, let's use
section titles in all YP docs.

(From yocto-docs rev: 0f44b6027f16cc37260abc7e00042d98e2e0427f)

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/migration-2.3.rst

@@ -198,7 +198,7 @@ The following changes took place for BitBake:
    fetcher passes the new parameter through the ``SVN_SSH`` environment
    variable during the :ref:`ref-tasks-fetch` task.
 
-   See the ":ref:`bitbake:svn-fetcher`"
+   See the ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-fetching:subversion (svn) fetcher (\`\`svn://\`\`)`"
    section in the BitBake
    User Manual for additional information.
 

documentation/ref-manual/migration-2.6.rst

@@ -278,7 +278,7 @@ The following changes have occurred:
    specifying list items to remove, be aware that leading and trailing
    whitespace resulting from the removal is retained.
 
-   See the ":ref:`bitbake:removing-override-style-syntax`"
+   See the ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:removal (override style syntax)`"
    section in the BitBake User Manual for a detailed example.
 
 .. _migration-2.6-systemd-configuration-now-split-out-to-system-conf:

documentation/ref-manual/ref-devtool-reference.rst

@@ -352,7 +352,7 @@ particular recipe.
       `maintainers.inc <http://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/conf/distro/include/maintainers.inc>`_
       file.
 
-   -  If the recipe is using the :ref:`bitbake:git-fetcher`
+   -  If the recipe is using the :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-fetching:git fetcher (\`\`git://\`\`)`
       rather than a
       tarball, the commit hash points to the commit that matches the
       recipe's latest version tag.

documentation/ref-manual/ref-tasks.rst

@@ -122,7 +122,7 @@ If the ``do_deploy`` task re-executes, any previous output is removed
 
 Fetches the source code. This task uses the
 :term:`SRC_URI` variable and the argument's prefix to
-determine the correct :ref:`fetcher <bitbake:bb-fetchers>`
+determine the correct :ref:`fetcher <bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
 module.
 
 .. _ref-tasks-image:

documentation/ref-manual/ref-variables.rst

@@ -3062,7 +3062,7 @@ system and gives an overview of their function and contents.
             section in the Yocto Project Development Tasks Manual.
 
          -  Using ``IMAGE_INSTALL`` with the
-            :ref:`+= <bitbake:appending-and-prepending>`
+            :ref:`+= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
             BitBake operator within the ``/conf/local.conf`` file or from
             within an image recipe is not recommended. Use of this operator
             in these ways can cause ordering issues. Since
@@ -7018,7 +7018,7 @@ system and gives an overview of their function and contents.
       protocols are highly dependent on particular BitBake Fetcher
       submodules. Depending on the fetcher BitBake uses, various URL
       parameters are employed. For specifics on the supported Fetchers, see
-      the ":ref:`Fetchers <bitbake:bb-fetchers>`" section in the
+      the ":ref:`Fetchers <bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`" section in the
       BitBake User Manual.
 
       -  ``file://`` - Fetches files, which are usually files shipped