bluetooth: Add new LE Meta subtype descriptions

[antoniovazquezblanco]

Checklist:

• If you are new to Scapy: I have checked CONTRIBUTING.md (esp. section submitting-pull-requests)
• I squashed commits belonging together
• I added unit tests or explained why they are not relevant
• I executed the regression tests (using cd test && ./run_tests or tox)
• If the PR is still not finished, please create a Draft Pull Request

Minor LE Meta improvements.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.60%. Comparing base (1346522) to head (d8598aa).
Report is 11 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4622      +/-   ##
==========================================
- Coverage   81.62%   81.60%   -0.02%     
==========================================
  Files         359      359              
  Lines       86052    86052              
==========================================
- Hits        70237    70227      -10     
- Misses      15815    15825      +10     

Files with missing lines	Coverage Δ
scapy/layers/bluetooth.py	90.35% <100.00%> (ø)

... and 9 files with indirect coverage changes