docs: fix hardcoded link warning messages

Sphinx complains about hardcoded links which can be replaced by an
extlink.

So let's apply its recommendations.

(From yocto-docs rev: a385999029942ae12b6b5d0dddc3fbbd3be13a02)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reported-by: Quentin Schulz <foss+yocto@0leil.net>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/bsp-guide/bsp.rst

@@ -166,8 +166,9 @@ section.
 #. *Determine the BSP Layer You Want:* The Yocto Project supports many
    BSPs, which are maintained in their own layers or in layers designed
    to contain several BSPs. To get an idea of machine support through
-   BSP layers, you can look at the `index of
-   machines <&YOCTO_RELEASE_DL_URL;/machines>`__ for the release.
+   BSP layers, you can look at the
+   :yocto_dl:`index of machines </releases/yocto/yocto-&DISTRO;/machines>`
+   for the release.
 
 #. *Optionally Clone the meta-intel BSP Layer:* If your hardware is
    based on current Intel CPUs and devices, you can leverage this BSP
@@ -877,7 +878,7 @@ Yocto Project:
    your BSP layer as listed in the ``recipes.txt`` file, which is found
    in ``poky/meta`` directory of the :term:`Source Directory`
    or in the OpenEmbedded-Core Layer (``openembedded-core``) at
-   https://git.openembedded.org/openembedded-core/tree/meta.
+   :oe_git:`/openembedded-core/tree/meta`.
 
    You should place recipes (``*.bb`` files) and recipe modifications
    (``*.bbappend`` files) into ``recipes-*`` subdirectories by

documentation/migration-guides/migration-3.4.rst

@@ -140,7 +140,7 @@ configuration provided and tested by the Yocto Project, there is
 simply no sense in continuing to enable prelink.
 
 There's also a concern that no one is maintaining the code, and there
-are open bugs (including `this serious one <https://bugzilla.yoctoproject.org/show_bug.cgi?id=14429>`__).
+are open bugs (including :yocto_bugs:`this serious one </show_bug.cgi?id=14429>`).
 Given that prelink does intricate address arithmetic and rewriting
 of binaries the best option is to disable the feature. It is recommended
 that you consider disabling this feature in your own configuration if

documentation/overview-manual/yp-intro.rst

@@ -217,8 +217,8 @@ your Metadata, the easier it is to cope with future changes.
    -  Use Board Support Package (BSP) layers from silicon vendors when
       possible.
 
-   -  Familiarize yourself with the `Yocto Project curated layer
-      index <https://www.yoctoproject.org/software-overview/layers/>`__
+   -  Familiarize yourself with the
+      :yocto_home:`Yocto Project curated layer index</software-overview/layers/>`
       or the :oe_layerindex:`OpenEmbedded layer index <>`.
       The latter contains more layers but they are less universally
       validated.

documentation/ref-manual/system-requirements.rst

@@ -320,7 +320,7 @@ If you would prefer not to use the ``install-buildtools`` script, you can instea
 download and run a pre-built buildtools installer yourself with the following
 steps:
 
-1. Locate and download the ``*.sh`` at &YOCTO_RELEASE_DL_URL;/buildtools/
+1. Locate and download the ``*.sh`` at :yocto_dl:`/releases/yocto/yocto-&DISTRO;/buildtools/`
 
 2. Execute the installation script. Here is an example for the
    traditional installer::