Add proxy section to the Stealthy Playwright ReadMe

Author: mdmintz

examples/cdp_mode/playwright/ReadMe.md

@@ -139,6 +139,73 @@ with sync_playwright() as p:
     sb.sleep(3)
 ```
 
+--------
+
+### 🎭 Proxy with auth in <b translate="no">Stealthy Playwright Mode</b>:
+
+To use an authenticated proxy in Stealthy Playwright Mode, **do these two things**:<br />**1.** Set the`proxy` arg when launching Chrome.
+-- Eg: `sb_cdp.Chrome(proxy="USER:PASS@IP:PORT")` or `cdp_driver.start_async("USER:PASS@IP:PORT")`.<br />**2.** Open the URL with SeleniumBase **before** using `endpoint_url` to connect to the browser with Playwright.
+
+⚠️ If any trouble with the above, set `use_chromium=True` so that you can use the base Chromium browser, which still allows extensions, unlike regular branded Chrome, which removed the `--load-extension` command-line switch. (*An extension is used to set the auth for the proxy, which is needed when CDP can't set the proxy alone, such as for navigation after the initial page load*).
+
+In the sync format, use `sb.open(url)` to open the url before connecting Playwright:
+```python
+sb = sb_cdp.Chrome(use_chromium=True, proxy="user:pass@server:port")
+sb.open(url)
+endpoint_url = sb.get_endpoint_url()
+# ...
+```
+
+In the async format, use, `driver.get(url)` to open the url before connecting Playwright:
+```python
+driver = await cdp_driver.start_async(use_chromium=True, proxy="user:pass@server:port")
+await driver.get(url)
+endpoint_url = driver.get_endpoint_url()
+# ...
+```
+
+Here's an example of using an authenticated proxy with Stealthy Playwright Mode:<br />(The URL is opened before attaching Playwright so that proxy settings take effect)
+```python
+from playwright.sync_api import sync_playwright
+from seleniumbase import sb_cdp
+
+sb = sb_cdp.Chrome(use_chromium=True, proxy="user:pass@server:port")
+sb.open(url)
+endpoint_url = sb.get_endpoint_url()
+
+with sync_playwright() as p:
+    browser = p.chromium.connect_over_cdp(endpoint_url)
+    context = browser.contexts[0]
+    page = context.pages[0]
+    # ...
+```
+(Fill in the `url` and the `proxy` details to complete the script.)
+
+Here's the same thing for the `async` format:
+```python
+import asyncio
+from playwright.async_api import async_playwright
+from seleniumbase import cdp_driver
+
+async def main():
+    driver = await cdp_driver.start_async(use_chromium=True, proxy="user:pass@server:port")
+    await driver.get(url)
+    endpoint_url = driver.get_endpoint_url()
+
+    async with async_playwright() as p:
+        browser = await p.chromium.connect_over_cdp(endpoint_url)
+        context = browser.contexts[0]
+        page = context.pages[0]
+        # ...
+
+if __name__ == "__main__":
+    loop = asyncio.new_event_loop()
+    loop.run_until_complete(main())
+```
+(Fill in the `url` and the `proxy` details to complete the script.)
+
+--------
+
 For more examples, see [examples/cdp_mode/playwright](https://github.com/seleniumbase/SeleniumBase/tree/master/examples/cdp_mode/playwright).
 
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