Update README with changed install instructions for pip #459

Job	Run time
pycharm-security	1m 34s
flake8	54s
pytest (Python 3.8, ubuntu-latest)	3m 31s
pytest (Python 3.9, ubuntu-latest)	3m 21s
pytest (Python 3.10, ubuntu-latest)	3m 20s
pytest (Python 3.11, ubuntu-latest)	4m 9s
pytest (Python 3.8, macos-latest)	7m 57s
pytest (Python 3.9, macos-latest)	9m 7s
pytest (Python 3.10, macos-latest)	10m 0s
pytest (Python 3.11, macos-latest)	9m 59s
pytest (Python 3.8, windows-latest)	18m 10s
pytest (Python 3.9, windows-latest)	18m 38s
pytest (Python 3.10, windows-latest)	18m 20s
pytest (Python 3.11, windows-latest)	17m 8s
pytest (Pandoc 2.11)	4m 28s
pytest (Pandoc 2.12)	3m 23s
pytest (Pandoc 2.13)	4m 24s
pytest (Pandoc 2.14)	4m 16s
pytest (Pandoc 2.15)	3m 21s
pytest (Pandoc 2.16)	3m 59s
pytest (Pandoc 2.17)	3m 45s
pytest (Pandoc 2.18)	3m 28s
pytest (Pandoc 2.19)	3m 26s
pypi-packages	1m 14s
conda-build (ubuntu-latest)	6m 8s
conda-build (macos-latest)	12m 11s
conda-build (windows-latest)	22m 49s
	3h 23m 0s

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