Add note on traceability in the docs

[ewjoachim]

Building for the good ideas expressed in pypi/warehouse#6378 (comment)

Checklist:

• Tests
  • (not applicable?)
• Documentation
  • (not applicable?)

[codecov]

Codecov Report

Merging #26 (ba9df35) into master (27b8428) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #26   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          140       148    +8     
  Branches        11        11           
=========================================
+ Hits           140       148    +8     

Impacted Files	Coverage Δ
pypitoken/__init__.py	100.00% <100.00%> (ø)
pypitoken/token.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1ae1c45...ba9df35. Read the comment docs.