Docs: Deprecate need for `FIX_APPMANIFEST` for `hlds` in usage exampl… #537

Job	Run time
test-build-hlds	1m 46s
test-build-srcds	1m 52s
test-game-image-game-version	4s
dockerhub-description-hlds	0s
publish-draft-release	5s
dockerhub-description-srcds	0s
update-draft-release	0s
	3m 47s

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