docs: adding documentation for bentoctl

[jjmachan]

1. Introduction
2. Quickstart
3. Core Concepts
4. Operator List

[codecov]

Codecov Report

Merging #71 (20d147f) into main (5818a1d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #71   +/-   ##
=======================================
  Coverage   64.76%   64.76%           
=======================================
  Files          15       15           
  Lines         752      752           
=======================================
  Hits          487      487           
  Misses        265      265           

Flag	Coverage Δ
unit-tests	64.76% <ø> (ø)

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