discoverability: Links from repos to `docs.ros.org`?

[eacousineau]

First off: These docs are awesome! Thank you!

In crawling around to tinker with Bazel stuff (using company acct, @EricCousineau-TRI), I initially missed these docs.
I knew a little bit about index.ros.org/docs/ros2, but, uh, hadn't looked deeply enough here.

One thing that would have motivated me to more closely read the docs would have been links from the code repositories back to one of the forms of documentation (either docs.ros.org or index.ros.org/docs), and possibly the package's docs on index.ros.org.

Examples (at current SHA1s):
https://github.com/ros2/rclcpp/tree/0a44344f4332f3a8818291dc46c5491192b41c78 - No README / overview?
https://github.com/ros2/rclpy/tree/28a77736f1d5ffd13a1dc065e066fab3a89f27f2 - README, but no link to docs?
https://github.com/ros2/rmw/tree/0d7db0fee279a226285e63a594c5448ef4815c57 - No README
https://github.com/ros2/rmw_implementation/tree/7c2f2c8956a58c085602aca6a5cf82a21e2c6089 - No README

If it would help, I'd be more than happy to take a stab at adding this information to one of these packages as a PR, then making the parallel PRs (which could possibly trigger an update for the package description?).

EDIT(2020/05/30): Have not yet had a chance to delve into this :(

[jacobperron]

Following ros2/ros_core_documentation#13 (comment), I think adding README with links to ROS Index and the relevant API docs makes sense. PRs welcome :)

[clalancette]

We're deprecating this repository (the contents have been moved over to https://github.com/ros2/ros2_documentation), so I'm going to move this issue over there.