addressed the feedback from @burakemir in PR #76

[deesh-code]

Here's what I accomplished:

Changes Made

 1. Removed Standalone HTML Files: 
   * Deleted docs/grammar_railroad_core.html
    
   * Deleted docs/grammar_railroad_full.html 
    
   * Deleted docs/README_grammar.md
 2. Integrated into Sphinx Documentation:
   * Created readthedocs/grammar.md with comprehensive MyST markdown documentation
    
   * Updated readthedocs/index.md to include "Grammar Reference" in the table of contents
    
   * The grammar documentation is now part of the main Sphinx-based user documentation system
 3. Updated Generator Script:
   * Modified scripts/generate_railroad_diagrams.py to generate MyST markdown instead of HTML
    
   * Script now creates documentation that integrates seamlessly with the Sphinx system
    
   * Kept the EBNF file generation for users who want to use external tools
 4. Maintained External Tool Support:
   * Kept docs/grammar.ebnf file for users who want to use https://www.bottlecaps.de/rr/ui 

(https://www.bottlecaps.de/rr/ui)

   * Users can copy the EBNF grammar and paste it into external railroad diagram generators

Key Features of the New Implementation

 * Sphinx Integration: Grammar documentation is now part of the main readthedocs system
 * MyST Markdown: Uses the same format as other documentation files
 * Comprehensive Coverage: Includes both core Datalog and extended Mangle grammar
 * Rich Examples: Provides practical code examples for each grammar construct
 * Easy Maintenance: Single source of truth that can be regenerated from the ANTLR grammar
 * External Tool Support: Users can still use bottlecaps.de for interactive railroad diagrams

[google-cla]

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[deesh-code]

Is anyone here to review

[burakemir]

Hey there, I was waiting for you to sign the CLA.