Minor corrections to the API documentation

* The right web address for configuring API keys seems to have changed
* Minor clarification on how basic authentication works (it's illustrated in the examples later, but can't hurt to be precise)

Signed-off-by: William Lachance <wlach@protonmail.com>

api.md

@@ -3,7 +3,7 @@
 The Tailscale API is a (mostly) RESTful API. Typically, POST bodies should be JSON encoded and responses will be JSON encoded.
 
 # Authentication
-Currently based on {some authentication method}. Visit the [admin panel](https://api.tailscale.com/admin) and navigate to the `Keys` page. Generate an API Key and keep it safe. Provide the key as the user key in basic auth when making calls to Tailscale API endpoints.
+Currently based on {some authentication method}. Visit the [admin panel](https://login.tailscale.com/admin) and navigate to the `Settings` page. Generate an API Key and keep it safe. Provide the key as the user key in basic auth when making calls to Tailscale API endpoints (leave the password blank).
 
 # APIs