Add documentation for StructuralContext to README

[TotalVerb]

Partially address #298 (still need docs for Serialization, but I only had time to write these so far).

I apologize for the lack of documentation when I implemented these features — it had been on my TODO list but slipped from the mind. I will make another PR with docs and examples for Serialization soon.

[codecov]

Codecov Report

Merging #300 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #300      +/-   ##
==========================================
+ Coverage    98.2%   98.21%   +<.01%     
==========================================
  Files           8        8              
  Lines         390      392       +2     
==========================================
+ Hits          383      385       +2     
  Misses          7        7

Impacted Files	Coverage Δ
src/Parser.jl	99.01% <0%> (ø)	⬆️

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[twavv]

This looks awesome! Thank you for doing this!

It might be worth investing in setting up proper docs (à la Documenter.jl) because it might make the readme a bit bloated (definitely something that could be punted down the road though).

[TotalVerb]

Indeed, I agree that proper docs would be the right solution! In general, there is a lot of work that could be done to modernize this package (most of it was written back in the Julia 0.3/0.4 days), and adhering to new conventions is one thing we have been lagging on. But I guess it is better to have the documentation somewhere first.

We will keep #298 open until we have docs for Serialization too, which is perhaps actually even more important.