docs: API reference and getting-started guide for developers.pezkuwichain.io (#21)

* docs: generate the API reference for developers.pezkuwichain.io

Add TypeDoc (0.28.20) and `yarn docs`, which builds the reference for the
nine public API packages from src/ into build-docs/, with a landing page
and a getting-started guide whose examples were run against the live
network. The PR workflow builds it so a broken doc comment or config is
caught before merge.

docs/ held only a redirect to polkadot.js.org; it now holds the guide
sources. The README, packages/api/README.md and three CHANGELOG entries
linked to js.pezkuwichain.app, a domain that is not ours and is listed
for sale; they now point to developers.pezkuwichain.io, the Pezkuwi
Portal, or the upstream polkadot.js.org pages the entries came from.

* ci(docs): deploy the reference to developers.pezkuwichain.io

On every master push that changes the generated reference, build it with
`yarn docs` and publish it to the web host the same way pezkuwi-apps
publishes the portal: an approved production environment holds the deploy
key, the bundle is unpacked into releases/<sha>, and going live is one
rename of the current symlink. The switch is checked through nginx for the
public name (deploy sha, index, main.js, search index) and rolled back if
the new release is not served. workflow_dispatch with rollback_to makes an
earlier release live again.

Release-bot version bumps ([CI Skip]) and changes that cannot affect the
output do not ask for an approval.

packages/api/README.md

@@ -7,13 +7,13 @@ The API wrappers provide a standard interface for use -
 - A static `.create(<optional ApiOptions>)` that returns an API instance when connected, decorated and ready-to use. ApiOptions can include an optional WsProvider and optional custom type definitions `{ provider: <Optional WsProvider>, types: <Optional RegistryTypes> }`.
 - The above is just a wrapper for `new Api(<optional ApiOptions>) `, exposing the `isReady` getter
 - `api.rpc.<section>.<method>` provides access to actual RPC calls, be it for queries, submission or retrieving chain information
-  - [RPC (node interface)](https://js.pezkuwichain.app/docs/bizinikiwi/rpc)
+  - browse them live in the [Pezkuwi Portal, RPC calls](https://js.pezkuwichain.io/#/rpc)
 - `api.query.<section>.<method>` provides access to chain state queries. These are dynamically populated based on what the runtime provides
-  - [Storage chain state (runtime node interface)](https://js.pezkuwichain.app/docs/bizinikiwi/storage)
+  - browse them live in the [Pezkuwi Portal, chain state](https://js.pezkuwichain.io/#/chainstate)
 - `api.tx.<section>.<method>` provides the ability to create a transaction, like chain state, this list is populated from a runtime query
-  - [Extrinsics (runtime node interface)](https://js.pezkuwichain.app/docs/bizinikiwi/extrinsics)
+  - browse them live in the [Pezkuwi Portal, extrinsics](https://js.pezkuwichain.io/#/extrinsics)
 - `api.consts.<section>.<constant>` provides access to the module constants (parameter types).
-  - [Constants (runtime node interface)](https://js.pezkuwichain.app/docs/bizinikiwi/constants)
+  - browse them live in the [Pezkuwi Portal, constants](https://js.pezkuwichain.io/#/chainstate/constants)
 
 ## API Selection