Extract track-specific help instructions from `config/exercise_readme.go.tmpl`

Each track needs a file that contains track-specific instructions on how to get help. The contents of this document are only presented to the student when using the CLI. This file lives at `exercises/shared/.docs/help.md`. **You almost certainly already have this information, but need to move it to the correct place.**

For v2 tracks, this information was (usually) included in the readme template found at `config/exercise_readme.go.tmpl`. As such, tracks can extract the help instructions from the `config/exercise_readme.go.tmpl` file to the `exercises/shared/.docs/help.md` file.

See https://github.com/exercism/csharp/pull/1557/files for an example PR.

# Tracking

https://github.com/exercism/v3-launch/issues/50

Start by reading config/exercise_readme.go.tmpl and compare its track-specific help content with exercises/shared/.docs/help.md. Move the relevant instructions to the help document so the CLI presents them to students, then verify that the template no longer contains the extracted content and that the help file is complete.

Written by the indexing model from the issue text.