Fix description of \uXXXX escape sequences #922

Job	Run time
cpp-lib-build (macos-11, clang, ON)	1m 54s
build (macos-11, tool)	1m 52s
cpp-lib-build (macos-11, clang, OFF)	8m 0s
build (macos-11, cpp)	32m 59s
cpp-lib-build (macos-11, gcc, ON)	4m 40s
build (macos-11, csharp)	12m 7s
cpp-lib-build (macos-11, gcc, OFF)	7m 32s
build (macos-11, dart)	6m 47s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 44s
build (macos-11, go)	5m 11s
build (macos-11, java)	2m 28s
cpp-lib-build (ubuntu-20.04, clang, OFF)	5m 41s
build (macos-11, javascript)	3m 14s
cpp-lib-build (ubuntu-20.04, gcc, ON)	4m 53s
build (macos-11, typescript)	17m 49s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	8m 51s
build (macos-11, php)	2m 27s
cpp-lib-build (windows-2022, clang, ON)	8m 9s
build (macos-11, python3)	1m 51s
cpp-lib-build (windows-2022, clang, OFF)	9m 37s
build (ubuntu-20.04, tool)	1m 38s
cpp-lib-build (windows-2022, cl)	8m 16s
build (ubuntu-20.04, cpp)	23m 30s
build (ubuntu-20.04, csharp)	9m 14s
build (ubuntu-20.04, dart)	6m 45s
build (ubuntu-20.04, go)	4m 2s
build (ubuntu-20.04, java)	2m 21s
build (ubuntu-20.04, javascript)	2m 11s
build (ubuntu-20.04, typescript)	19m 31s
build (ubuntu-20.04, php)	2m 39s
build (ubuntu-20.04, python3)	3m 27s
build (windows-2022, tool)	3m 7s
build (windows-2022, cpp)	45m 40s
build (windows-2022, csharp)	14m 33s
build (windows-2022, dart)	10m 6s
build (windows-2022, go)	10m 2s
build (windows-2022, java)	3m 3s
build (windows-2022, javascript)	4m 32s
build (windows-2022, typescript)	35m 32s
build (windows-2022, php)	2m 59s
build (windows-2022, python3)	3m 43s
	6h 6m 37s

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