Doc: add doxygen documents #216

Job	Run time
macos / build_macos (Release, 6.6.2, clang_64, x64-osx)	8m 18s
doxygen / build_doxygen	2m 35s
mingw / build mingw (Release)	16m 26s
macos / build_macos (Release, 5.15.2, clang_64, x64-osx)	3m 10s
android / build_android (Release, android_arm64_v8a, 6.6.2)	1m 27s
mingw / build mingw (Debug)	12m 33s
macos / build_macos (Release, 5.12.12, clang_64, x64-osx)	3m 7s
android / build_android (Release, android_armv7, 6.6.2)	1m 24s
macos / build_macos (Debug, 6.6.2, clang_64, x64-osx)	7m 47s
android / build_android (Release, android_x86_64, 6.6.2)	1m 34s
macos / build_macos (Debug, 5.15.2, clang_64, x64-osx)	3m 13s
msvc / build_msvc (Release, 6.6.2)	20m 45s
macos / build_macos (Debug, 5.12.12, clang_64, x64-osx)	3m 34s
msvc / build_msvc (Release, 5.15.2)	10m 58s
ubuntu / build_ubuntu (Release)	5m 38s
msvc / build_msvc (Release, 5.12.12)	15m 15s
ubuntu / build_ubuntu (Debug)	7m 13s
msvc / build_msvc (Debug, 6.6.2)	32m 20s
msvc / build_msvc (Debug, 5.15.2)	20m 24s
msvc / build_msvc (Debug, 5.12.12)	9m 4s
deploy	0s
	3h 6m 45s

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