man: add manpages all binaries

[clebergnu]

To match Debian Policy every binary should have manpage. Add RST docs for every binary which has --help command.

For the runners, actual description was taken from their sources.

Reference: https://github.com/avocado-framework/avocado/pull/5050

[mr-avocado[bot]]

Dear contributor, Avocado is currently under sprint #103, which is due to release an LTS (Long Term Stability) release. Please avoid merging changes that do not fall into these categories:

• Bug fixes
• Usability Improvements
• Documentation updates

As for the Avocado utility modules (“avocado.utils”) it is OK to introduce new functionality, but changes to the existing APIs (including interface and behavior) should be avoided. These kind of changes should wait until sprint #104.

[clebergnu]

Closing this issue for now, due to change in priorities.