api.md: remove descriptions from TOC (#4561)

api.md

@@ -22,9 +22,9 @@ Currently based on {some authentication method}. Visit the [admin panel](https:/
 * **[Tailnets](#tailnet)**
   - ACLs
     - [GET tailnet ACL](#tailnet-acl-get)
-    - [POST tailnet ACL](#tailnet-acl-post): set ACL for a tailnet
-    - [POST tailnet ACL preview](#tailnet-acl-preview-post): preview rule matches on an ACL for a resource
-	- [POST tailnet ACL validate](#tailnet-acl-validate-post): run validation tests against a new or existing ACL
+    - [POST tailnet ACL](#tailnet-acl-post)
+    - [POST tailnet ACL preview](#tailnet-acl-preview-post)
+	- [POST tailnet ACL validate](#tailnet-acl-validate-post)
   - [Devices](#tailnet-devices)
     - [GET tailnet devices](#tailnet-devices-get)
   - [Keys](#tailnet-keys)