Merge pull request #18847 from clayjohn/doc_panorama_sky

doc/classes/PanoramaSky.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="PanoramaSky" inherits="Sky" category="Core" version="3.1">
 	<brief_description>
+		A type of [Sky] used to draw a background texture.
 	</brief_description>
 	<description>
+		A resource referenced in an [Environment] that is used to draw a background. The Panorama sky functions similar to skyboxes in other engines except it uses a equirectangular sky map instead of a cube map.
 	</description>
 	<tutorials>
 	</tutorials>
@@ -12,6 +14,7 @@
 	</methods>
 	<members>
 		<member name="panorama" type="Texture" setter="set_panorama" getter="get_panorama">
+			[Texture] to be applied to the PanoramaSky.
 		</member>
 	</members>
 	<constants>