Migrate Ruler documentation from Wiki

[vipulgupta2048]

This PR migrates wiki-pages of Ruler Activity from https://wiki.sugarlabs.org/go/Activities/ruler [1]
to the help-activity, for the user to access easily from the device (using the shortcut alt + shift + h)

To-do

• When PR is merged; Depreciate [1] and images associated with it, link the wiki-page back to the repository.
• Add a README.md to sugarlabs/ruler pointing back to user-documentation.

Status - Incomplete

[quozl]

Reviewed to 69b9796.

• link in commit message does not work; should be Ruler not ruler,
• content refers to bugs.sugarlabs.org instead of Ruler issues on GitHub,
• unwilling to merge documentation for an activity that does not even work, as this will cause learners to try to download and use the activity once the help.sugarlabs.org site or Help Activity is updated, see Fails with Fedora 28 sugarlabs/ruler#4, Fails with Ubuntu 16.04 sucrose sugarlabs/ruler#3, and Fails with Ubuntu 18.04 sugarlabs/ruler#6.

[vipulgupta2048]

I honestly didn't take a look at the issues, after the script was done. I understand your unwillingness and accept the decision made. Reading the documentation for a program that doesn't even work is just a waste of time and energy. I will take care of the same next time onwards (Noted in my checklist)
Till then, I think we can keep this PR open, till the issues for Ruler activity has been resolved.

[vipulgupta2048]

• Commit message amended.
• Reporting bugs now refer to making new issues and viewing all issues open on Ruler's GitHub repository.
  Thanks for the review.

[quozl]

Reviewed again. Continuing to delay merge until work is done to fix Ruler activity.

[quozl]

Cherry-picked as 976f3ff.