docs: fix a couple of links

This was broken RST syntax, and lead to a couple of rogue cite-tags in
the rendered HTML.

Reviewed-by: Yonggang Luo <luoyonggang@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19494>

docs/amber.rst

@@ -39,7 +39,7 @@ enable that logic, you need to pass the ``-Damber=true`` flag to Meson.
 Documentation
 -------------
 
-On `docs.mesa3d.org <https://docs.mesa3d.org/>`, we currently only
+On `docs.mesa3d.org <https://docs.mesa3d.org/>`__, we currently only
 publish the documentation from our main branch. But you can view the
 documentation for the Amber branch `here
 <https://gitlab.freedesktop.org/mesa/mesa/-/tree/21.3/docs>`_.

docs/drivers/vc4.rst

@@ -78,7 +78,7 @@ problem, that's still the best.  If the problem takes a long time to
 reproduce or you can't capture it in a trace, describing how to
 reproduce and including a GPU hang dump would be the most
 useful. Install `vc4-gpu-tools
-<https://github.com/anholt/vc4-gpu-tools/>` and use
+<https://github.com/anholt/vc4-gpu-tools/>`__ and use
 ``vc4_dump_hang_state my-app.hang``. Sometimes the hang file will
 provide useful information.
 

docs/thanks.rst

@@ -25,7 +25,7 @@ somewhat dated, unfortunately.
 -  **Bogdan Sikorski** wrote the GLU NURBS and polygon tessellator in
    Mesa.
 -  **Charlie Wallace** wrote the MS-DOS driver.
--  **CJ Beyer** was the `www.mesa3d.org <https://www.mesa3d.org>`
+-  **CJ Beyer** was the `www.mesa3d.org <https://www.mesa3d.org>`__
    webmaster.
 -  **Darren Abbott** provided the OS/2 driver.
 -  **David Bucciarelli** wrote and maintained the 3Dfx Glide driver.