ref-manual: document new github-releases class

Newly added class in 4.1.

(From yocto-docs rev: 391750e417d7a6b88222e03aa0a57ea87d9f618a)

Signed-off-by: Paul Eggleton <paul.eggleton@microsoft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/classes.rst

@@ -659,6 +659,20 @@ the GNU ``gettext`` internationalization and localization system. All
 recipes building software that use ``gettext`` should inherit this
 class.
 
+.. _ref-classes-github-releases:
+
+``github-releases``
+===================
+
+For recipes that fetch release tarballs from github, the ``github-releases``
+class sets up a standard way for checking available upstream versions
+(to support ``devtool upgrade`` and the Automated Upgrade Helper (AUH)).
+
+To use it, add ``github-releases`` to the inherit line in the recipe,
+and if the default value of :term:`GITHUB_BASE_URI` is not suitable,
+then set your own value in the recipe. You should then use ``${GITHUB_BASE_URI}``
+in the value you set for :term:`SRC_URI` within the recipe.
+
 .. _ref-classes-gnomebase:
 
 ``gnomebase.bbclass``

documentation/ref-manual/variables.rst

@@ -2768,6 +2768,13 @@ system and gives an overview of their function and contents.
       The directory in which a local copy of a Git repository is stored
       when it is cloned.
 
+   :term:`GITHUB_BASE_URI`
+      When inheriting the :ref:`github-releases <ref-classes-github-releases>`
+      class, specifies the base URL for fetching releases for the github
+      project you wish to fetch sources from. The default value is as follows::
+
+         GITHUB_BASE_URI ?= "https://github.com/${BPN}/${BPN}/releases/"
+
    :term:`GLIBC_GENERATE_LOCALES`
       Specifies the list of GLIBC locales to generate should you not wish
       to generate all LIBC locals, which can be time consuming.