doc: Add docs how to add and update test status of flashchips

For reference, link to doc about adding new chip
on the old website:
https://wiki.flashrom.org/Development_Guidelines#Adding/reviewing_a_new_flash_chip

Docs on how to update test status of flashchips never existed before.

Change-Id: I8dde689f2a0430ae10d3fa68bee727c5a9d70aec
Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/80205
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>

doc/contrib_howtos/how_to_mark_chip_tested.rst

@@ -0,0 +1,46 @@
+==========================
+How to mark chip as tested
+==========================
+
+flashrom has a massive amount of flashchips definitions, not all of them are fully tested. The reason for this is:
+in some situations chip definition can be introduced based on the values that the datasheet claims,
+but without testing on hardware. In this case chip definition is marked as not tested, **TEST_UNTESTED**. If later
+someone uses the chip for real, and it works, the chip definition can be (and should be) updated, and operations
+which run successfully should be marked as tested.
+
+To mark the chip as tested, someone (one of the maintainers, or one of the contributors) need to send a patch to update
+the list of flashchips. It can be you, and *yes it can be your first patch to flashrom!* If this is your first patch,
+make sure you read the :doc:`/dev_guide/development_guide` and set up dev environment locally. If this is not possible, you
+are welcome to send test results to the mailing list, see :ref:`mailing list`.
+
+Instructions below assume you went through Development guide, and set up environment and repository locally.
+
+To begin with, make sure you have full logs from all the operations that you have run successfully and want to
+mark as tested. **Providing full logs which indicate successful run is required to mark chip as tested.**
+
+Information about tested status of the chip is stored in ``flashchips.c``, specifically in the ``.tested`` member
+of ``struct flashchip``.
+
+Relevant definitions and available options are in ``include/flash.h``, specifically see the definition of:
+
+* ``enum test_state``
+* ``struct tested`` (inside ``struct flashchip``)
+* pre-defined macros for ``struct tested``, all of them follow the pattern ``#define TEST_xxx_yyy``
+
+Choose the correct value depending on the operations that you have tested successfully. And then:
+
+#. Open ``flashchips.c`` and find the definition of your chip.
+#. Check the tested status of the chip. If you tested *not* on the latest HEAD (perhaps on the latest released version,
+   or on flashrom built a month ago, etc), it is possible that tested status has been updated already. If the status
+   has not been updated,
+#. Update ``.tested`` value to the one which reflects current test status. Note that not all the operations have to be
+   tested at once: maybe you tested only probe and read, then mark just that.
+#. Make sure flashrom builds successfully, and all the unit tests pass.
+#. For commit title, use the string ``flashchips: Mark <chip name> as tested for <operations>``.
+#. Provide the logs in commit message, you can use flashrom paste service at `paste.flashrom.org <https://paste.flashrom.org>`_
+   or any other paste service. As a plan B, you can post message on the :ref:`mailing list`, attach the logs to the post,
+   and then add the link to the post to the commit message.
+#. Follow :doc:`/dev_guide/development_guide` and send your patch for review.
+#. Go through review process until your patch gets approved (see Development guide for more details on this).
+
+To see the examples of such patches, have a look at commit history of ``flashchips.c``.