migration-guides: stop including documents with ".. include"

This prevented variables from being substituted through the
code in yocto-vars.py, at least in the files included this way.

Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
(From yocto-docs rev: ac4e4b167964dd4548fb3d90cf9c63580a70b6e3)

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

documentation/migration-guides/index.rst

@@ -12,8 +12,8 @@ to move to one release of the Yocto Project from the previous one.
 .. toctree::
 
    migration-general
-   migration-4.0
-   migration-3.4
+   release-4.0
+   release-3.4
    migration-3.3
    migration-3.2
    migration-3.1

documentation/migration-guides/migration-3.4.rst

@@ -1,6 +1,3 @@
-Release 3.4 (honister)
-======================
-
 Migration notes for 3.4 (honister)
 ----------------------------------
 
@@ -274,6 +271,3 @@ Miscellaneous
   examples in :term:`EXTRA_USERS_PARAMS`.
 
 
-.. include:: release-notes-3.4.rst
-.. include:: release-notes-3.4.1.rst
-.. include:: release-notes-3.4.2.rst

documentation/migration-guides/migration-4.0.rst

@@ -265,5 +265,3 @@ Miscellaneous changes
   when parsing recipes. Any code depending on the previous behaviour will no longer
   work - change any such code to explicitly use appropriate path variables instead.
 
-
-.. include:: release-notes-4.0.rst

documentation/migration-guides/release-3.4.rst

@@ -0,0 +1,10 @@
+Release 3.4 (honister)
+======================
+
+.. toctree::
+
+   migration-3.4
+   release-notes-3.4
+   release-notes-3.4.1
+   release-notes-3.4.2
+

documentation/migration-guides/release-4.0.rst

@@ -0,0 +1,7 @@
+Release 4.0 (kirkstone)
+=======================
+
+.. toctree::
+
+   migration-4.0
+   release-notes-4.0