Update docs for dependencies with yield

[tiangolo]

📝 Update docs for dependencies with yield. Clarify docs.

[github-actions]

🚀 Deployed on https://5e499a816861a7b3f0dcff43--fastapi.netlify.com

[codecov]

Codecov Report

Merging #986 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            master      #986    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files          294       294            
  Lines         7553      7717   +164     
==========================================
+ Hits          7553      7717   +164     

Impacted Files	Coverage Δ
tests/main.py	100.00% <0.00%> (ø)	⬆️
tests/test_path.py	100.00% <0.00%> (ø)	⬆️
tests/test_query.py	100.00% <0.00%> (ø)	⬆️
tests/test_fakeasync.py	100.00% <0.00%> (ø)	⬆️
tests/test_application.py	100.00% <0.00%> (ø)	⬆️
tests/test_empty_router.py	100.00% <0.00%> (ø)	⬆️
docs/src/app_testing/main.py	100.00% <0.00%> (ø)	⬆️
tests/test_security_oauth2.py	100.00% <0.00%> (ø)	⬆️
docs/src/events/tutorial001.py	100.00% <0.00%> (ø)	⬆️
docs/src/events/tutorial002.py	100.00% <0.00%> (ø)	⬆️
... and 78 more

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[github-actions]

🚀 Deployed on https://5e499b39984507f437a4ad02--fastapi.netlify.com