chore: Unify env bool processing

[AJIOB]

• Unify env bool processing
• Upper & mixed-case values are also accepted
• Actualize main readme file with the latest feature list location
• Return some missed spaces

[codecov-commenter]

Codecov Report

Attention: 18 lines in your changes are missing coverage. Please review.

Comparison is base (6ebc516) 30.89% compared to head (fbb9b60) 30.63%.

Files	Patch %	Lines
src/config.rs	18.18%	7 Missing and 11 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2103      +/-   ##
==========================================
- Coverage   30.89%   30.63%   -0.27%     
==========================================
  Files          53       53              
  Lines       20033    20011      -22     
  Branches     9717     9697      -20     
==========================================
- Hits         6189     6130      -59     
+ Misses       7947     7932      -15     
- Partials     5897     5949      +52     

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[Xuanwo]

Thanks!