docs: Reference latest version of zed_extension_api (#16954)

This PR updates the extension docs to reference the latest version of
the `zed_extension_api`.

Release Notes:

- N/A

docs/src/extensions/developing-extensions.md

@@ -53,7 +53,7 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
-zed_extension_api = "0.0.6"
+zed_extension_api = "0.1.0"
 ```
 
 Make sure to use the latest version of the [`zed_extension_api`](https://crates.io/crates/zed_extension_api) available on crates.io.