Added Embassy in the wild docs page with links to some projects

Based off an example, noting what to copy, what to change and why

Briefly summarizing how to require embassy crates via github

All steps tested and proven working at the time of writing

New: delaying_a_task.adoc, copied as-is from the wiki and placed in the
navigation until we have a better place for it (or remove/replace it)

index: Tweaked the structure, added some content from the wiki, and made
some general copy edits to improve clarity.

getting_started.adoc: Corrected various out-of-date information, added
troubleshooting tips from the wiki, added some new information, various
other small edits.

basic_application.adoc: Corrected out-of-date information, various clarifications
and edits.

After these changes, IMO most of the content on the github wiki is no longer
necessary and can be removed for clarity. The few sections I didn‘t integrate
or copy over were either out of date or unfinished.