README.md: State what can be built as of Milestone 17 ...

... and add a Status section

README.md

@@ -1,13 +1,28 @@
 # Branch `[master]`
 
-As of Milestone 16 (2021-06-24), this branch can be used to build the releases
-current at the end of June 2021 of ROS 2 **dashing**, **eloquent**, **foxy**,
-**galactic**, and **rolling** and ROS 1 **melodic** and **noetic** with the
-**honister** OpenEmbedded release series.
+As of Milestone 17 (2022-06-05), this branch can be used to build the releases
+current in mid-November 2021 of ROS 2 **foxy** and **galactic** and ROS 1
+**melodic** and **noetic** with the **kirkstone** OpenEmbedded release series as
+of the beginning of December 2021.
+
+The mid-November 2021 release (and earlier releases) of ROS 2 **rolling** can no
+longer be built because the commits referenced by its recipes have been removed
+rom the `[release/rolling/*]`branches of the release repositories.
+
+A "best effort" has been made to keep the EOL-ed ROS 2 **dashing** and
+**eloquent** distros buildable, but some of the packages that are used to create
+the `ros-image-world` image do not build. However, the `ros-image-core` image
+does successfully build.
 
 Instructions for using `meta-ros` are
 [here](https://github.com/ros/meta-ros/wiki/OpenEmbedded-Build-Instructions).
 
+## Status
+
+With the exception of the commits added to complete Milestone 17, this repository
+has not been maintained since December 2021. Its future maintenance was
+discussed in the
+[OSRF TSC January 2022 meeting post](https://discourse.ros.org/t/os-2-tsc-meeting-january-20th-2022/23986/2).
 
 ## History