update readme.md

Signed-off-by: Ahmet Alp Balkan <[email protected]>

README.md

@@ -25,6 +25,8 @@ Run. It’s not language-specific and works with external tools and binaries.
 - [Installation](#installation)
 - [Quickstart](#quickstart)
 - [Architecture](#architecture)
+- [Troubleshooting](#troubleshooting)
+- [Limitations and Known Issues](#limitations-and-known-issues)
 
 <!-- tocstop -->
 
@@ -70,6 +72,12 @@ ENTRYPOINT ["runsd", "--", "/app"]
 In the example above, change `<VERSION>` to a version number in the [Releases
 page](https://github.com/ahmetb/runsd).
 
+After installing `runsd`, it will have no effect while running locally. However,
+while on Cloud Run, you can now query other services by name over `http://`.
+
+Note that your traffic is still secure –as the request is upgraded to HTTPS
+before it leaves your container.
+
 ## Quickstart
 
 You can deploy [this](./example) sample application to Cloud Run to try out
@@ -128,6 +136,20 @@ If the logs don't help you troubleshoot the issues, feel free to open an issue
 on this repository; however, don’t have any expectations about when it will be
 resolved. Patch and more tests are always welcome.
 
+## Limitations and Known Issues
+
+1. HTTP protocol corner cases and streaming (SSE or WebSockets) untested.
+1. All names like `http://NAME` will resolve to a Cloud Run URL even  if they
+   don't exist. Therefore, for example, if `http://hello` doesn't exist, it will
+   still be routed to a URL as if it existed, and it will get HTTP 404.
+1. Similar to previous item `http://metadata` will be assumed as a Cloud Run
+   service instead of [instance metadata
+   server](https://cloud.google.com/compute/docs/storing-retrieving-metadata).
+   To prevent this, use its FQDN `metadata.google.internal.` with a trailing
+   dot.
+1. No structured logging support, but this should not impact you since the tools
+   is not supposed to log anything except the errors.
+
 -----
 
 This is not an official Google project.