improve require docs

- describe critical dependency warning

src/content/api/module-methods.mdx

@@ -433,3 +433,13 @@ __webpack_modules__[require.resolveWeak(`./page/${page}`)];
 ```
 
 T> `require.resolveWeak` is the foundation of _universal rendering_ (SSR + Code Splitting), as used in packages such as [react-universal-component](https://github.com/faceyspacey/react-universal-component). It allows code to render synchronously on both the server and initial page-loads on the client. It requires that chunks are manually served or somehow available. It's able to require modules without indicating they should be bundled into a chunk. It's used in conjunction with `import()` which takes over when user navigation triggers additional imports.
+
+If the module source contains a require that cannot be statically analyzed, critical dependencies warning is emitted.
+
+Example code:
+
+```javascript
+someFn(require);
+require.bind(null);
+require(variable);
+```