Update environment variable documentation

[JamieMagee]

This documentation hasn't been updated in a while, so we were missing documentation on:

• DisableRustCliScan
• PIP_INDEX_URL
• PipReportOverrideBehavior
• PipReportSkipFallbackOnFailure
• PipReportFileLevelTimeoutSeconds
• PipReportDisableFastDeps
• PipReportIgnoreFileLevelIndexUrl
• PipReportPersistReports

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.2%. Comparing base (a2b219a) to head (0e09ad1).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #1546    +/-   ##
======================================
  Coverage   90.2%   90.2%            
======================================
  Files        423     423            
  Lines      35452   35632   +180     
  Branches    2207    2262    +55     
======================================
+ Hits       31996   32170   +174     
- Misses      3001    3006     +5     
- Partials     455     456     +1     

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[github-actions]

👋 Hi! It looks like you modified some files in the Detectors folder.
You may need to bump the detector versions if any of the following scenarios apply:

• The detector detects more or fewer components than before
• The detector generates different parent/child graph relationships than before
• The detector generates different devDependencies values than before

If none of the above scenarios apply, feel free to ignore this comment 🙂