Update release notes, etc., for the 1.47.2 release #125

Job	Run time
Build and test with ASAN enabled	1m 39s
Build and test with clang	1m 40s
Cross-compile for Android (aarch64)	46s
Cross-compile for Android (armv7a)	42s
Build and test with gcc	1m 7s
Build and test with gcc -m32	1m 15s
Build and test on macOS	1m 22s
Cross-compile for Android (i686)	46s
Build and test with UBSAN enabled	1m 49s
Cross-compile for Android (x86_64)	33s
Build mke2fs on Windows with mingw32	2m 3s
Build mke2fs on Windows with mingw64	1m 54s
	15m 36s

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