Update Propeller architecture documentation #2841

Job	Run time
unpack-envvars	1s
Docker Build Images (flyteadmin) / build_docker	2m 48s
Docker Build Images (flytecopilot) / build_docker	2m 5s
Docker Build Images (datacatalog) / build_docker	2m 21s
Docker Build Images (flytepropeller) / build_docker	3m 18s
Build Images / Build & Push Image (datacatalog) / Push to Github Registry	2m 41s
Build Images / Build & Push Image (flytecopilot) / Push to Github Registry	2m 47s
Build Images / Build & Push Image (flyteadmin) / Push to Github Registry	3m 15s
Build Images / Build & Push Image (flytepropeller) / Push to Github Registry	3m 33s
Build Images / Build & Push Image (flytescheduler) / Push to Github Registry	3m 23s
Check Go Generate (datacatalog) / Go Generate	1m 45s
Check Go Generate (flyteadmin) / Go Generate	2m 27s
Check Go Generate (flytecopilot) / Go Generate	1m 30s
Check Go Generate (flytepropeller) / Go Generate	2m 30s
Lint (datacatalog) / Run Lint	2m 23s
Lint (flyteadmin) / Run Lint	3m 15s
Lint (flyteidl) / Run Lint	1m 54s
Lint (flyteplugins) / Run Lint	2m 57s
Lint (flytepropeller) / Run Lint	3m 15s
Lint (flytestdlib) / Run Lint	2m 32s
Unit Tests (datacatalog) / Run Unit Test	3m 18s
Unit Tests (flyteadmin) / Run Unit Test	4m 38s
Unit Tests (flytecopilot) / Run Unit Test	2m 50s
Unit Tests (flyteplugins) / Run Unit Test	4m 11s
Unit Tests (flytepropeller) / Run Unit Test	4m 26s
Unit Tests (flytestdlib) / Run Unit Test	3m 54s
Integration Test (flyteadmin) / Integration tests	5m 44s
	1h 19m 41s

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