Short doc about custom query prefixes

Author: vojoup

README.md

@@ -1,3 +1,30 @@
 # webRPC react-query client
 
 Server synchronization made easy & type-safe!
+## How to use
+
+First, you'll need an api contract, ideally in the webRPC format.
+Then create an instance of your contract and pass it as an argument to the WebRPCClient constructor.
+It should look something like this:
+
+```ts
+const ContractInstance = new Chat('hostname', customFetch)
+export const client = new WebRpcClient(ContractInstance)
+```
+
+Import `client` where you need to make your API calls and let type inference guide your way!
+
+## Differentiating queries and mutations
+
+If you want to make the distinction between a query and a mutation even clearer, you can define custom _query prefixes_.
+You do so by adding a generic type to your `WebRpcClient` instance.
+
+```ts
+const ContractInstance = new Chat('hostname', fetch)
+const client = new WebRpcClient<typeof ContractInstance, ['get', 'list']>(
+  ContractInstance,
+)
+```
+
+With this configuration, you can only use `client.useQuery` hook with paths that start with either `'get'` or `'list'`.
+Any other method from your contract will be considered a _mutation_. If you choose not to provide _query prefixes_, you will be able to call both `client.useQuery` and `client.useMutation` with any path from your contract.