Tidy up release docs so that they're up to date

[owenatgov]

What/Why

A general sweep of our release docs following the release of 5.3.1. Specific changes:

• Update places where we reference our "sprint board" with the correct link and the word "cycle" instead of "sprint"
• Remove a reference to squads as we've abandoned the 2 squad way of working following the release of 5.0
• Make use of github's alerts markdown for the warning in the docs on preview publishing
• Reformat the npm version command so that the version number placeholder is at the end of the command, meaning it's easier to replace it when the command is copy/pasted into a terminal
• Clarify that the version number required in the npm version command is just the number, no v's
• Fix a stray typo

[github-actions[bot]]

:clipboard: Stats

File sizes

File	Size
dist/govuk-frontend-development.min.css	113.24 KiB
dist/govuk-frontend-development.min.js	42.21 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	87.21 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	81.95 KiB
packages/govuk-frontend/dist/govuk/all.mjs	4.17 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend-component.mjs	359 B
packages/govuk-frontend/dist/govuk/govuk-frontend.min.css	113.23 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.js	42.2 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.55 KiB

Modules

File	Size (bundled)	Size (minified)
all.mjs	77.67 KiB	40.19 KiB
accordion.mjs	22.71 KiB	12.85 KiB
button.mjs	5.98 KiB	2.69 KiB
character-count.mjs	22.4 KiB	9.92 KiB
checkboxes.mjs	5.83 KiB	2.83 KiB
error-summary.mjs	7.89 KiB	3.46 KiB
exit-this-page.mjs	17.1 KiB	9.26 KiB
header.mjs	4.46 KiB	2.6 KiB
notification-banner.mjs	6.26 KiB	2.62 KiB
password-input.mjs	15.15 KiB	7.25 KiB
radios.mjs	4.83 KiB	2.38 KiB
skip-link.mjs	4.39 KiB	2.18 KiB
tabs.mjs	10.13 KiB	6.11 KiB

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Action run for 0022d53a3bf3793fcab58a6df2368acfea382a43