metainfo: Fix some xml snippets

docs/02-for-app-authors/03-metainfo-guidelines/index.md

@@ -431,15 +431,15 @@ Console applications with no desktop file can define them in the Metainfo
 file.
 
 ```xml
-  <categories>
-    <category>Development</category>
-    <category>Science</category>
-  </categories>
+<categories>
+  <category>Development</category>
+  <category>Science</category>
+</categories>
 
-  <keywords>
-    <keyword>IDE</keyword>
-    <keyword>development</keyword>
-  </keywords>
+<keywords>
+  <keyword>IDE</keyword>
+  <keyword>development</keyword>
+</keywords>
 ```
 
 ## Icons
@@ -651,7 +651,6 @@ The following tags can have translations: `name`, `name` child tag in
 The `description` tag has to be translated by each `<p>` and `<li>` tags.
 
 ```xml
-
 <name>App name</name>
 <name xml:lang="de">Translated App name</name>
 
@@ -712,7 +711,7 @@ output devices an app supports.
 
 The `requires` tag denotes an absolute requirement on the property
 while the `recommends` and `supports` tag is a recommendation of a
-non-essential requirement. Software stores uses this information to
+non-essential requirement. Software stores use this information to
 categorise apps and show device support information.
 
 ### Control
@@ -721,31 +720,31 @@ If the app supports and works on both desktop and touch devices, it
 should have the below metadata.
 
 ```xml
-  <!-- Desktop AND mobile supported -->
-  <recommends>
-    <control>keyboard</control>
-    <control>pointing</control>
-    <control>touch</control>
-  </recommends>
+<!-- Desktop AND mobile supported -->
+<recommends>
+  <control>keyboard</control>
+  <control>pointing</control>
+  <control>touch</control>
+</recommends>
 ```
 
 If it only works on desktop devices, it should have
 
-```
-  <!-- ONLY desktop supported -->
-  <requires>
-    <control>keyboard</control>
-    <control>pointing</control>
-  </requires>
+```xml
+<!-- ONLY desktop supported -->
+<requires>
+  <control>keyboard</control>
+  <control>pointing</control>
+</requires>
 ```
 
 If it only works on touch devices it should have
 
-```
-  <!-- ONLY mobile supported -->
-  <requires>
-    <control>touch</control>
-  </requires>
+```xml
+<!-- ONLY mobile supported -->
+<requires>
+  <control>touch</control>
+</requires>
 ```
 
 Additionally, `tablet`, `gamepad`, and [other properties](https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-relations-control)
@@ -772,32 +771,32 @@ screen sizes,  use any value `>=1` and `<=360` with the `ge`
 relation.
 
 ```xml
-  <requires>
-    <!-- Mobile/tablet AND desktop supported -->
-    <display_length compare="ge">360</display_length>
-  </requires>
+<requires>
+  <!-- Mobile/tablet AND desktop supported -->
+  <display_length compare="ge">360</display_length>
+</requires>
 ```
 
 To indicate support for _only_ desktop screen sizes, use any value
 `>=361` with the `ge` relation. Usually `768` is used as a baseline
 here.
 
 ```xml
-  <requires>
-    <!-- ONLY desktop supported -->
-    <display_length compare="ge">768</display_length>
-  </requires>
+<requires>
+  <!-- ONLY desktop supported -->
+  <display_length compare="ge">768</display_length>
+</requires>
 ```
 
 To indicate support for _only_ mobile/tablet screen sizes use the
 any value between `>=768` and `<=1279` with the `le` relation.
 Usually `1279` is used as a baseline here.
 
 ```xml
-  <requires>
-    <!-- ONLY mobile/tablet supported -->
-    <display_length compare="le">1279</display_length>
-  </requires>
+<requires>
+  <!-- ONLY mobile/tablet supported -->
+  <display_length compare="le">1279</display_length>
+</requires>
 ```
 
 ## Manifest location