add page to guide about enums #1560

Job	Run time
Check	1m 5s
Verify that web-sys is compiled correctly	51s
Clippy	1m 36s
Rustfmt	14s
Run js-sys crate tests	2m 18s
Run native tests	1m 50s
Run wasm-bindgen crate tests with multithreading enabled	1m 37s
Run wasm-bindgen crate tests (unix)	7m 34s
Run web-sys crate tests	3m 42s
build_benchmarks	52s
build_examples	3m 33s
build_nightly	1m 41s
dist_linux_aarch64_gnu	2m 58s
dist_linux_x86_64_musl	2m 42s
dist_macos_x86_64	2m 1s
Build and test the deno example	50s
Test TypeScript output of wasm-bindgen	1m 3s
Run UI compile-fail tests	4m 22s
Run wasm-bindgen-webidl crate tests	2m 15s
dist_macos_aarch64	2m 27s
dist_windows	2m 54s
doc_api	1m 15s
doc_book	11s
test_examples	2m 28s
deploy	57s
	53m 16s

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