docs(new): add TSDoc comments to Puppeteer (#6032)

new-docs/puppeteer.puppeteer.errors.md

@@ -9,3 +9,25 @@
 ```typescript
 get errors(): PuppeteerErrors;
 ```
+
+## Remarks
+
+Puppeteer methods might throw errors if they are unable to fulfill a request. For example, `page.waitForSelector(selector[, options])` might fail if the selector doesn't match any nodes during the given timeframe.
+
+For certain types of errors Puppeteer uses specific error classes. These classes are available via `puppeteer.errors`
+
+## Example
+
+An example of handling a timeout error:
+
+```js
+try {
+  await page.waitForSelector('.foo');
+} catch (e) {
+  if (e instanceof puppeteer.errors.TimeoutError) {
+    // Do something if this is a timeout.
+  }
+}
+
+```
+