🌱 Improve weekly PR update generation script and documentation

[typeid]

What this PR does / why we need it:
Currently, the usage of the weekly PR update generation script is a bit confusing because it requires checking out the right branches as well as providing the right milestones for these branches. This PR attempts to address this issue by clarifying the documentation and updating the script to only use the branch parameter for the whole flow.

This PR updates the Generate weekly PR updates to post in Slack flow:

• the script has been updated
  • it now pulls from github instead of needing a local correct checkout and right branch
  • the time range was previously off by a day, this is now fixed
  • --milestone is now --branch and should no more cause confusion between the relationship of branch to milestone
  • a parameter check for --branch was added
• the documentation was updated
  • added a full example of commands to run during an ongoing release cycle
  • updated the usage to branch instead of milestone

Which issue(s) this PR fixes
Fixes #10008

/area release

[k8s-ci-robot]

Hi @typeid. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[willie-yao]

/ok-to-test

[willie-yao]

Nice work! This will be a great improvement to the current tool 🚀

[typeid]

I'm not fully sure why the lint workflow fails.

[willie-yao]

/lgtm

Great work!!

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 1bf8e39c2418e59c115a73c266c1e79ff9755e06

[cahillsf]

looks like this generic example is in conflict with the provided examples, specifically the --branch arg: ./bin/weekly --since 2024-01-22 --until 2024-01-28 --branch main

[typeid]

Should be more generic now, thanks for pointing that out Stephen.

[cahillsf]

would you mind pushing a small update to this line too:

cluster-api/hack/tools/release/weekly/main.go

Line 193 in b973c82

fmt.Println("_Thanks to all our contributors!_ 😊")

i think the underscores should be * or something else that highlights this line to bold or italicize, right now they just render in slack as underscores

[typeid]

/retest

[willie-yao]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 3d33eb8f1231778c4c4cdc1f89815116b9abfe42

[cahillsf]

very nice! thanks for this update 👍

/lgtm

[sbueringer]

/approve

(given lgtm's above. I didn't review the code change)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

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