docs: replace the rocket emoji in the banner and oracle headings

[GigaHierz]

Follow-up to #2361: no rocket emoji in any copy.

What changed

• docs.json: the banner starts with 🤖 instead of 🚀, as the previous banner did. The wording is unchanged.
• tooling/oracles/{supra,redstone,quex-oracles}.mdx: removes the 🚀 from the three ## What is … headings (AGENTS.md already says no emoji in headings).
• AGENTS.md section 4: adds the rule, "No rocket emoji in any copy: pages, headings, banners or PR text. If a banner needs an emoji, use 🤖."

grep -rn "🚀" over *.mdx and *.json now returns nothing. The removed heading emoji produced no anchors that anything links to.

Verification

$ mint broken-links --check-redirects
success no broken links found
$ bash scripts/check-orphans.sh
No orphan pages found.

🤖 Generated with Claude Code

[GigaHierz]

@eddiemessiah, this follows up your banner PR (#2361). The banner now uses 🤖 instead of 🚀, because we don't use rocket emoji in any copy. The same rule is now in AGENTS.md section 4, and I removed the rocket from three oracle page headings that had one. You can't be added as a formal reviewer on this repo, so please have a look here and say if anything is off.

[palango]

This does what it says. git grep "🚀" at the PR head finds nothing in any file type, the docs.json change is just the banner line and merges cleanly with #2344, and nothing in the repo or the redirects links to the old what-is-… fragments, so the slug change breaks nothing.

Two small things, neither blocking. The Quex and RedStone pages still have 📈, 🔥, 👨‍💻 and 🙋‍♂️ headings a few lines below the ones you fixed, and most of them are questions, both of which AGENTS.md section 3 already rules out. Since you're in these files, could you clean those up too? Nothing links to them. And I'd make the new AGENTS.md line more general, see the inline comment.

[palango]

Section 3 (line 74) already bans emoji in headings, so this mostly restates it for one emoji. "PR text" isn't page copy, and this file is served as a public page on docs.celo.org. Pinning 🤖 fits the current banner but would read oddly on one about a hardfork or an operator deadline. Something like "No emoji in body copy; a banner may open with one emoji that fits its subject" would still hold next year. Your call.

[palango]

Lines 28, 32, 38, 44 and 50 still have emoji headings, and 32 and 38 are the same section twice. Worth stripping while you're here.

[palango]

Same here: lines 28, 34, 42 and 46 still have emoji headings.