[bitnami/mastodon] replace all instances of JupyterHub with Mastodon in values.yaml

[jessebot]

Description of the change

This replaces all instances of JupyterHub with Mastodon.

Benefits

This makes the comments in the values.yaml and the README docs more clear. I believe this was just a copy paste cleanup issue. No biggie.

Possible drawbacks

none that I can think of

Applicable issues

no issues that I see immediately

Additional information

let me know if you'd like me to remove the Chart.yaml version bump

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
• Title of the pull request follows this pattern [bitnami/<name_of_the_chart>] Descriptive title
• All commits signed off and in agreement of Developer Certificate of Origin (DCO)

[FraPazGal]

Thanks for fixing these typos @jessebot! Could you actually remove the chart version bump? Given this is just a cosmetic change affecting documentation I don't think we should release a new chart's version, which users will need to update to.

[jessebot]

@FraPazGal sure, no problem, I have done this. Let me know if there's anything else I can help with :)

[FraPazGal]

All done @jessebot, thanks again for the contribution!