feat: Update documentation and export knowledge base classes

[chyroc]

• Added usage instructions for knowledge document in README
• Exported knowledge related classes in cozepy/__init__.py
• Added two static methods to DocumentChunkStrategy and DocumentUpdateRule for quick creation

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.

Project coverage is 74.94%. Comparing base (268c5b3) to head (fa21728).
Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
cozepy/knowledge/documents/__init__.py	73.33%	4 Missing ⚠️

@@            Coverage Diff             @@
##             main      #29      +/-   ##
==========================================
- Coverage   75.42%   74.94%   -0.48%     
==========================================
  Files          27       29       +2     
  Lines         883      998     +115     
==========================================
+ Hits          666      748      +82     
- Misses        217      250      +33     

Flag	Coverage Δ
	74.94% <76.47%> (-0.48%)	⬇️

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Files with missing lines	Coverage Δ
cozepy/__init__.py	100.00% <100.00%> (ø)
cozepy/workspaces/__init__.py	77.41% <100.00%> (-0.71%)	⬇️
cozepy/knowledge/documents/__init__.py	74.25% <73.33%> (ø)

... and 1 file with indirect coverage changes