docs: add documentation for configuring notifications in GCP (#5545) #2

Job	Run time
unpack-envvars	1s
flyteadmin integration tests image / build_docker	4m 45s
Build Images / Build & Push Image (datacatalog) / Push to Github Registry	4m 24s
Build Images / Build & Push Image (flyteadmin) / Push to Github Registry	6m 4s
Build Images / Build & Push Image (flytecopilot) / Push to Github Registry	4m 24s
Build Images / Build & Push Image (flytepropeller) / Push to Github Registry	6m 11s
Build Images / Build & Push Image (flytescheduler) / Push to Github Registry	5m 35s
Dry Run Goreleaser	8m 3s
Test Getting started	7m 52s
Check Go Generate (datacatalog) / Go Generate	1m 48s
Check Go Generate (flyteadmin) / Go Generate	2m 21s
Check Go Generate (flytecopilot) / Go Generate	1m 43s
Check Go Generate (flytectl) / Go Generate	2m 11s
Check Go Generate (flytepropeller) / Go Generate	2m 6s
Lint (datacatalog) / Run Lint	2m 27s
Lint (flyteadmin) / Run Lint	2m 58s
Lint (flytectl) / Run Lint	2m 57s
Lint (flyteidl) / Run Lint	1m 45s
Lint (flyteplugins) / Run Lint	3m 1s
Lint (flytepropeller) / Run Lint	2m 51s
Lint (flytestdlib) / Run Lint	2m 29s
Unit Tests (flyteadmin) / Run Unit Test	4m 18s
Unit Tests (datacatalog) / Run Unit Test	2m 47s
Unit Tests (flytecopilot) / Run Unit Test	2m 26s
Unit Tests (flytectl) / Run Unit Test	3m 17s
Unit Tests (flyteplugins) / Run Unit Test	3m 37s
Unit Tests (flytestdlib) / Run Unit Test	3m 36s
Unit Tests (flytepropeller) / Run Unit Test	4m 5s
Integration Test (flyteadmin) / Integration tests	5m 40s
	1h 45m 42s

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