Update release notes, etc., for the 1.47.2 release #129

Job	Run time
Build and test with ASAN enabled	1m 34s
Build and test with clang	1m 24s
Cross-compile for Android (aarch64)	54s
Cross-compile for Android (armv7a)	37s
Build and test with gcc	57s
Build and test on macOS	1m 29s
Build and test with gcc -m32	1m 8s
Cross-compile for Android (i686)	46s
Cross-compile for Android (x86_64)	38s
Build and test with UBSAN enabled	1m 23s
Build mke2fs on Windows with mingw32	1m 59s
Build mke2fs on Windows with mingw64	2m 0s
	14m 49s

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