Add feature to Public API methods index page

Author: maria-robobug

docs/references/http-websocket-apis/public-api-methods/index.md

@@ -93,6 +93,7 @@ Use these methods to retrieve information about the current state of the `ripple
 * **[`server_state`](server-info-methods/server_state.md)** - Retrieve status of the server in machine-readable format.
 * **[`server_definitions`](server-info-methods/server_definitions.md)** - Retrieve a list of types and fields used for the XRPL's canonical binary format.
 * **[`manifest`](server-info-methods/manifest.md)** - Retrieve the latest ephemeral public key information about a known validator.
+* **[`feature`](server-info-methods/feature.md)** - Returns information about amendments this server knows about.
 
 ## [Clio Methods](clio-methods/index.md)