docs(@angular-devkit/build-angular): add descriptions for browser bui… #2095

Job	Run time
list	23s
workflow (modules-builder-tests)	1m 48s
workflow (devkit-core-tests-rerun)	1m 17s
workflow (build-cli)	1m 42s
workflow (devkit-core-tests)	1m 21s
workflow (build-unit-tests)	2m 23s
	8m 54s

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