Update docs with info about concurrent writes #553

Job	Run time
Test Posit Connect	4m 31s
Tests (3.8, ubuntu-latest, --workers 4 --tests-per-worker 1)	2m 6s
Build Docs	1m 25s
Tests (3.9, ubuntu-latest, --workers 4 --tests-per-worker 1)	2m 1s
Tests (3.10, ubuntu-latest, --workers 4 --tests-per-worker 1)	1m 39s
Tests (3.11, ubuntu-latest, --workers 4 --tests-per-worker 1)	1m 40s
Test a fork PR (no secrets)	0s
Tests (ubuntu-latest, 3.8, requirements/minimum.txt)	4m 10s
Tests (macos-latest, 3.10, --workers 4 --tests-per-worker 1 -k pins/tests)	3m 5s
Tests (windows-latest, 3.10, -k pins/tests)	18m 53s
Preview Docs:	49s
Release to pypi	0s
Publish Docs	0s
	40m 19s

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