docs: add initial command documentation

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 73.40%. Comparing base (c2373c5) to head (d9c4df7).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #16 +/- ## ======================================= Coverage 73.40% 73.40% ======================================= Files 30 30 Lines 2181 2181 ======================================= Hits 1601 1601 Misses 580 580 ```

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[github-actions[bot]]

Bencher

Report	Wed, March 13, 2024 at 20:49:08 UTC
Project	theseus-rs/rsql
Branch	command-documentation
Testbed	localhost

Benchmark	Latency	Latency Results nanoseconds (ns)
version	➖ (view plot)	45541000.000

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