Promote the v2 README to README.md ahead of the first v2 beta (#3014) #3183

Job	Run time
checks / pre-commit	1m 10s
checks / readme-snippets	15s
checks / docs	41s
checks / test (3.10, locked, ubuntu-latest)	1m 13s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.10, lowest-direct, windows-latest)	2m 6s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.11, locked, ubuntu-latest)	1m 15s
checks / test (3.11, lowest-direct, windows-latest)	1m 43s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 19s
checks / test (3.12, locked, windows-latest)	1m 45s
checks / test (3.12, locked, ubuntu-latest)	1m 26s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 6s
checks / test (3.14, locked, windows-latest)	2m 38s
checks / test (3.14, lowest-direct, windows-latest)	1m 34s
checks / test (3.13, lowest-direct, windows-latest)	2m 10s
checks / test (3.14, locked, ubuntu-latest)	2m 12s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.11, locked, windows-latest)	1m 44s
checks / test (3.13, locked, windows-latest)	1m 35s
checks / test (3.12, lowest-direct, windows-latest)	1m 51s
checks / test (3.13, locked, ubuntu-latest)	56s
checks / test (3.10, locked, windows-latest)	1m 40s
all-green	2s
	34m 4s

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