chore(assets): simplify content rating section

Generated by: https://hughsie.github.io/oars/generate.html

assets/freedesktop/org.zealdocs.zeal.appdata.xml.in

@@ -34,33 +34,5 @@
     </release>
   </releases>
   <update_contact>support@zealdocs.org</update_contact>
-  <content_rating type="oars-1.1">
-    <content_attribute id="violence-cartoon">none</content_attribute>
-    <content_attribute id="violence-fantasy">none</content_attribute>
-    <content_attribute id="violence-realistic">none</content_attribute>
-    <content_attribute id="violence-bloodshed">none</content_attribute>
-    <content_attribute id="violence-sexual">none</content_attribute>
-    <content_attribute id="violence-desecration">none</content_attribute>
-    <content_attribute id="violence-slavery">none</content_attribute>
-    <content_attribute id="violence-worship">none</content_attribute>
-    <content_attribute id="drugs-alcohol">none</content_attribute>
-    <content_attribute id="drugs-narcotics">none</content_attribute>
-    <content_attribute id="drugs-tobacco">none</content_attribute>
-    <content_attribute id="sex-nudity">none</content_attribute>
-    <content_attribute id="sex-themes">none</content_attribute>
-    <content_attribute id="sex-homosexuality">none</content_attribute>
-    <content_attribute id="sex-prostitution">none</content_attribute>
-    <content_attribute id="sex-adultery">none</content_attribute>
-    <content_attribute id="sex-appearance">none</content_attribute>
-    <content_attribute id="language-profanity">none</content_attribute>
-    <content_attribute id="language-humor">none</content_attribute>
-    <content_attribute id="language-discrimination">none</content_attribute>
-    <content_attribute id="social-chat">none</content_attribute>
-    <content_attribute id="social-info">none</content_attribute>
-    <content_attribute id="social-audio">none</content_attribute>
-    <content_attribute id="social-location">none</content_attribute>
-    <content_attribute id="social-contacts">none</content_attribute>
-    <content_attribute id="money-purchasing">none</content_attribute>
-    <content_attribute id="money-gambling">none</content_attribute>
-  </content_rating>
+  <content_rating type="oars-1.1" />
 </component>