docs: update Zed setup to use official elixir extension instead of fork (#32)

Zed extensions update path is a bit more complex than in other editors.
It's: 
- [x] Update Extension itself
- [x] Bump version
- [ ] Update extension in registry
[PR](zed-industries/extensions#5624)
- [ ] Update docs [PR](zed-industries/zed#53793)
- [ ] Release new Zed version

Anyway, main changes are merged we're just waiting they propagate to the
latest Zed release.
Meanwhile I'm updating docs to use official repo instead of my fork.

Author: flowerett

README.md

@@ -186,18 +186,17 @@ lspconfig.dexter.setup({})
 
 ### Zed
 
-Zed support is available via a dev extension while the official Elixir extension PR is in [review](https://github.com/zed-extensions/elixir/pull/115).
+Zed support is available via a **dev extension** while the update for built-in [extension registry](https://github.com/zed-industries/extensions/pull/5624) and [documentation](https://github.com/zed-industries/zed/pull/53793) is being merged.
 
 To install it:
 
-1. Clone the repo and checkout the branch:
+1. Clone the official extension repo:
    ```bash
-   git clone https://github.com/flowerett/zed-elixir-extensions.git
-   cd zed-elixir-extensions
-   git checkout add-dexter-support
+   git clone https://github.com/zed-extensions/elixir.git
+   cd elixir
    ```
 2. In Zed, open the command palette (`Cmd+Shift+P`) and run **zed: install dev extension**
-3. Select the cloned `zed-elixir-extensions` directory
+3. Select the cloned `elixir` directory
 
 Once installed, enable it in your Zed `settings.json`: