Create geolocation-requirements.md

[mmccool]

Problems found:

• Links to HTML, not MD
• How do we deal with variants or sub-requirements, e.g. "indoor geolocation"?

[mmccool]

Expanded use-case references. Additional considerations uncovered (may affect template):

• Use cases are arranged in a hierarchy, do we want to reflect that in the citations, or have a flat set of references?
• How to identify the variants mentioned in the coverage analysis? For now, have added variants after each citation, will add a "variants" section.

[lu-zero]

Probably a table would be better with a column for the multiple categorizations indoor/outdoor, static/dynamic, et cetera...

[mlagally]

All reviewers are requested to propose additional or modified text via the "suggestions" icon of the review page.