inline `jiter` README to fixup sdist build #699

Job	Run time
build pgo-optimized on ${{ matrix.os }} / ${{ matrix.interpreter }}	0s
build on ${{ matrix.os }} (${{ matrix.target }} - ${{ matrix.interpreter \|\| 'all' }}${{ (((matrix.os == 'linux') && format(' - {0}', (((matrix.manylinux == 'auto') && 'manylinux') \|\| matrix.manylinux))) \|\| '') }})	0s
build sdist	29s
bench	56s
fuzz skip	5m 23s
fuzz on ubuntu	5m 30s
lint	56s
fuzz on macos	5m 42s
resolve	12s
test jiter-python	50s
test build on ${{ matrix.os }}	0s
test build on ${{ matrix.target }}-${{ matrix.distro }}	0s
test rust-stable on ubuntu	39s
test rust-stable on macos	40s
test rust-1.75 on ubuntu	42s
test rust-nightly on ubuntu	1m 6s
inspect-pypi-assets	0s
check	1s
release	0s
release-python	0s
	23m 6s

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