docs: window.ethereum section in typescript.md (#993)

* docs: add Ethereum Provider section

* Update typescript.md

* Update typescript.md

---------

Co-authored-by: jxom <jakemoxey@gmail.com>

site/docs/typescript.md

@@ -188,3 +188,21 @@ The following utilities support type inference when you use const assertions or
 ## Configuring Internal Types
 
 For advanced use-cases, you may want to configure viem's internal types. Most of viem's types relating to ABIs and EIP-712 Typed Data are powered by [ABIType](https://abitype.dev). See ABIType's [documentation](https://abitype.dev/config.html) for more info on how to configure types.
+
+## `window` Polyfill
+
+By importing the `viem/window` Polyfill, the global `window.ethereum` will typed as an [`EIP1193Provider`](https://github.com/wagmi-dev/viem/blob/4bdbf15be0d61b52a195e11c97201e707fb616cc/src/types/eip1193.ts#L24-L26) (including a fully-typed `request` function & typed events). It may be `undefined` in cases where no browser extension Wallet is detected, or if rendered on the server.
+
+```ts
+import 'viem/window';
+
+if (typeof window !== 'undefined') {
+  const transaction = await window.ethereum.request({
+//      ^? const transaction: Transaction        
+    method: 'eth_getTransactionByHash',
+//  ^? (property) method: "eth_blockNumber" | "eth_call" | ...
+    params: ['0x...']
+//  ^? (property) params: [hash: Hash]
+  })
+}
+```