fix(docs): Fix admonition in contract class protocol spec #5684

Job	Run time
setup / start-builder	1m 7s
setup / setup	1m 0s
build	18m 44s
yarn-project-formatting	17m 13s
yarn-project-test	17m 9s
bb-native-tests	9m 41s
bb-bench-binaries	10m 49s
setup-bench / start-builder	1m 4s
setup-bench / setup	27s
bb-bench	5m 8s
e2e (e2e-browser)	1m 41s
e2e (e2e-docs-examples)	1m 14s
e2e (e2e-sandbox-example)	1m 46s
e2e (e2e-tests)	10m 4s
e2e (flakey-e2e-tests)	4m 10s
e2e (guides-dapp-testing)	3m 21s
e2e (guides-writing-an-account-contract)	1m 19s
e2e (integration-l1-publisher)	2m 13s
e2e (pxe)	55s
e2e (uniswap-trade-on-l1-from-l2)	6m 9s
merge-check	2s
notify	0s
	1h 55m 16s

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