docs: mark CRIS support as deprecated

This might be premature but while streamlining the avocado tests I
realised the only tests we have are "check-tcg" ones. The ageing
fedora-cris-cross image works well enough for developers but can't be
used in CI as we need supported build platforms to build QEMU.

Does this mean the writing is on the wall for this architecture?

Cc: Rabin Vincent <rabinv@axis.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240207163812.3231697-3-alex.bennee@linaro.org>

docs/about/deprecated.rst

@@ -192,6 +192,13 @@ in the QEMU object model anymore. ``power5+``, ``power5+_v2.1``,
 an alias, but for consistency these will get removed in a future
 release, too. Use ``power5p_v2.1`` and ``power7p_v2.1`` instead.
 
+CRIS CPU architecture (since 9.0)
+'''''''''''''''''''''''''''''''''
+
+The CRIS architecture was pulled from Linux in 4.17 and the compiler
+is no longer packaged in any distro making it harder to run the
+``check-tcg`` tests. Unless we can improve the testing situation there
+is a chance the code will bitrot without anyone noticing.
 
 System emulator machines
 ------------------------