update readme files

extension/README.md

@@ -1,2 +1,14 @@
-# Unshorten
-A Firefox extension to unshorten links from sites like Twitter.
+# Unshortener
+A Firefox extension to reveal links behind URL shorteners like Twitter and TinyURL.
+
+**Supported sites:**
+- t.co
+- tinyurl.com
+
+## Usage
+Build the extension and install it in Firefox. Right-clicking links will reveal a new
+"Unshorten link" option which will resolve the link and copy it to the clipboard.
+
+```shell
+make zip
+```

server/README.md

@@ -1,2 +1,14 @@
-# Unshorten Server
-Simple FastAPI app to unshorten URLs.
+# Unshortener Resolver API
+Simple FastAPI app to resolve links behind shortened URLs.
+
+**Supported sites**:
+- t.co
+- tinyurl.com
+
+## Usage
+Build and run the Docker container:
+
+```shell
+make build
+docker -d --name unshortener -p 8000:8000 unshortener-api
+```