manuals: update class references

Synchronizing with master whenever possible,
to make the branch easier to maintain.

(From yocto-docs rev: 825b1292ab08770b2d8cfdc1e11358a2790c1a1b)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

documentation/migration-guides/migration-1.5.rst

@@ -240,7 +240,7 @@ Automated Image Testing
 -----------------------
 
 A new automated image testing framework has been added through the
-:ref:`ref-classes-testimage*` classes. This
+:ref:`ref-classes-testimage` classes. This
 framework replaces the older ``imagetest-qemu`` framework.
 
 You can learn more about performing automated image tests in the

documentation/migration-guides/migration-2.6.rst

@@ -319,7 +319,7 @@ This section provides information about automatic testing changes:
    practices now dictate that you use the
    :term:`IMAGE_CLASSES` variable rather than the
    :term:`INHERIT` variable when you inherit the
-   :ref:`testimage <ref-classes-testimage*>` and
+   :ref:`testimage <ref-classes-testimage>` and
    :ref:`testsdk <ref-classes-testsdk>` classes used for automatic
    testing.