fix: various smaller issues in README

README.md

@@ -42,6 +42,7 @@ look up and return your dynamic content.
 ```yaml
 ---
 api: "0.13"
+api_compatibility: ["14"]
 space: My Hackerspace
 # This is a plugin invocation
 # with no arguments
@@ -60,6 +61,8 @@ sensors:
 ```json
 {
   "api": "0.13",
+  "api_compatibility": ["14"],
+  "space": "My Hackerspace",
   "state": {
     "open": true,
     "lastchange": 1575160777,
@@ -149,7 +152,7 @@ The content is served "almost-as-is" (apart from the conversion from
 YAML to JSON).
 
 To learn about how a SpaceAPI response should look like, have a look
-at [SpaceAPI: Getting Started][spaceapi-getting-started].
+at the [SpaceAPI Website][spaceapi].
 
 ### 4. Add Dynamic Content
 
@@ -290,9 +293,10 @@ from spaceapi_server import plugins
 def lookup_sensor(query, default=None):
     # Do something with the query
     result = ...
-    # If the loo
+    # If the lookup failed, return a default value
     if not result:
         return default or []
+    return result
 ```
 
 ```yaml
@@ -309,6 +313,5 @@ state: !lookup_sensor
 [pypi-bottle]: https://pypi.org/project/bottle/
 [pypi-yaml]: https://pypi.org/project/PyYAML/
 [mit]: https://gitlab.com/s3lph/spaceapi-server/blob/main/LICENSE
-[spaceapi-getting-started]: https://spaceapi.io/getting-started/
 [jinja]: https://jinja.palletsprojects.com/
 [registry]: https://gitlab.com/s3lph/spaceapi-server/container_registry