Document the anonymous public gateway write, and correct the docs that deny it exists

[yjkellyjoo]

Tracking issue for the docs-side work of ethersphere/DevRel#901.

The public gateway at api.gateway.ethswarm.org accepts anonymous, stamp-free, wallet-free writes, while our docs state that every upload requires the caller to supply a postage stamp. That contradiction has a measurable cost: a web-search answer synthesised from our own documentation concluded "you cannot upload files without running your own Bee node."

Verified behaviour

curl -X POST https://api.gateway.ethswarm.org/bzz --data '...'   -> HTTP 201 + reference
curl https://api.gateway.ethswarm.org/bzz/<ref>/                 -> content, byte-identical

The same reference resolves through bzz.link and bzz.limo, so the data does leave the origin gateway.

Blocker — do not start writing until this clears

This is not a protocol property. A proxy in front of the gateway attaches a postage stamp server-side. Documenting the anonymous write commits whoever funds that gateway to a subsidised, abuse-exposed free tier.

Before any page ships we need, from the gateway operator (@darkobas2 per the DevRel thread):

• Sign-off on documenting the anonymous write path at all.
• The actual limits: max upload size, retention / TTL, rate limits, and what happens when they are hit.
• Confirmation of the retrieval-side limits — HTML sites hit the Request Approval moderation page unless whitelisted.

Without a published fair-use and retention policy the docs become wrong in the opposite direction the moment the endpoint is rate-limited.

Statements to correct

Only the first is plainly false from the caller's point of view. The other two are true at the level they describe — uploads do always require a stamp; the proxy supplies one on the caller's behalf. The rewording has to preserve that distinction rather than flatly negating all three.

Location	Current text
static/cheatsheets/overview/index.html:214	"Not free to write. Every upload needs a funded light node and a stamp paid in xBZZ."
docs/develop/upload-and-download.md:16	"Uploads always require a postage stamp batch."
bee-js.ethswarm.org/docs/storage (separate repo)	"Any method in bee-js which writes data to Swarm requires the batch id of a valid, usable postage batch"

Proposed work in this repo

1. Add a "Store your first file, no wallet" section with the two verified curl commands and a short SWARM_GATEWAY_URL bee-js snippet. Placement is open — a new page under docs/develop/ linked from the landing page is the likely home, given docs/develop/gateway.md currently covers running a gateway rather than using the public one. Needs a sidebars.js entry either way.
2. Reword the two statements above once the operator input lands.
3. State the limits honestly on the same page: data and text work, HTML sites hit moderation, no persistence guarantee without your own stamp. Frame stamps as the production upgrade, not the entry fee.
4. Update static/llms.txt for the new page, and cover it in the llms-api.txt slice.

The bee-js docs change is out of scope here and belongs in the bee-js repo.

Related

• improve-gateways-section #683 — improve gateways section
• Add warning about public gateways and "get batch....storage not found" error #720 — warning about public gateways and the storage not found error