Update changelog for 5.1.0 #266

Job	Run time
lint-unit / markdownlint-cli2	3s
lint-unit / cookstyle	40s
lint-unit / markdown-link-check	15s
lint-unit / check-metadata	0s
lint-unit / rspec	35s
lint-unit / yamllint	7s
integration-macos (macos-latest, default)	3m 36s
integration-windows (windows-latest, default)	12m 52s
integration (centos-7, default)	1m 26s
integration (centos-stream-8, default)	1m 0s
integration (debian-11, default)	1m 12s
integration (debian-12, default)	1m 13s
integration (fedora-latest, default)	1m 0s
integration (oraclelinux-8, default)	1m 13s
integration (ubuntu-1804, default)	1m 22s
integration (ubuntu-2004, default)	1m 26s
integration (ubuntu-2204, default)	1m 19s
	29m 19s

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