[IMP] general: add notes about dev mode toggle

[StraubCreative]

Cherry pick of #1560.

Adds note warning users they need at least one app installed to be able to see the 'enable dev mode' option. Took me a while to figure this out as it doesn't seem to be mentioned anywhere (in these docs or in the Development Environment Set-uparticle).

[robodoo]

Pull request status dashboard.

[StraubCreative]

Hey @mivu-odoo super quick review here plz 🙏

[samueljlieber]

Hi @mivu-odoo 👋 I updated the rst and images per your suggestion as well as fixed some personal pronoun use and inconsistent capitalization. Ready for another review!

[samueljlieber]

Hi @mivu-odoo, thanks for the edits! I updated the doc and it is ready for another review. :)

[samueljlieber]

Hey @mivu-odoo 👋 ready for your final review! Thank you!

[samueljlieber]

Hi @StraubCreative 👋 this doc is ready for a final technical review! Thank you!

[StraubCreative]

8672fa2 addresses merge conflict from #2983, and I also added back in the internal hyperlink .. _developer-mode/mode-tools: referenced in developer/.../performance.rst so checks pass ✅

[StraubCreative]

Hi @odoo/doc-review this doc's ready for you :)

[tiku-odoo]

@AntoineVDV

CC: @StraubCreative, @samueljlieber

Thanks for your review. 👍 I've made the requested changes to this document. I just noticed that this PR was initially filed for 15.0 when this should apply to V14 ->V16, if I'm not mistaken. Here is the original PR: https://github.com/odoo/documentation/pull/1560

What are your thoughts on this?

Thanks, Tim

[samueljlieber]

Re-targeted via cherry pick: https://github.com/odoo/documentation/pull/3140

[AntoineVDV]

@samueljlieber @StraubCreative Instead of creating new PRs for new base branches, you could keep this PR open and force-push your new base on this one. It works just fine, keeps the history of the PR and its reviews, and allows reviewers to track which files are already reviewed.