Documentation fixes after the removal of the legacy C API (#1439) #1575

Job	Run time
ASAN	7m 35s
Bazel	5m 33s
Test Big Endian	9m 49s
macOS	14m 47s
UBSAN	7m 59s
Ubuntu 18.04 (Build: Debug, Compilers: gcc-6/g++-6, Shared Library: true)	9m 54s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	9m 8s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	9m 10s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: true)	14m 5s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: false)	14m 37s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	13m 58s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: true)	18m 59s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	13m 52s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: false)	19m 46s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: true)	8m 51s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: false)	8m 53s
	3h 6m 56s

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