Add indent in the document of session.py

[lin826]

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

Add indent for examples to improve readability.

[codecov]

Codecov Report

Merging #3966 (4a1f64e) into master (4aaed1d) will decrease coverage by 2.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3966      +/-   ##
==========================================
- Coverage   81.65%   79.22%   -2.44%     
==========================================
  Files         326      319       -7     
  Lines       75466    70252    -5214     
==========================================
- Hits        61625    55654    -5971     
- Misses      13841    14598     +757     

Impacted Files	Coverage Δ
scapy/layers/tls/session.py	87.87% <ø> (-0.34%)	⬇️

... and 119 files with indirect coverage changes

[gpotter2]

Suggested change

	vice versa. For instance you could do:
	vice versa. For instance you could do::