Added info and files required for store/showcase

linuxinstall/com.infinipaint.infinipaint.desktop

@@ -5,6 +5,7 @@ Type=Application
 Name=InfiniPaint
 Comment=Infinite canvas program
 Categories=Graphics;VectorGraphics;
+Keywords=whiteboard;notes;drawing;infinite;canvas;graphics;zoom
 
 Icon=com.infinipaint.infinipaint
 Exec=infinipaint %F

linuxinstall/com.infinipaint.infinipaint.metainfo.xml

@@ -36,7 +36,7 @@
     
     <description>
         <p>
-            InfiniPaint is a collaborative, infinite space, infinite zoom, canvas note-taking/drawing app. Unlike many other infinite canvas apps, although there is a specific zoom-in level limit, there is no zoom-out limit (at least up until the point your computer runs out of memory). This means that this app is very good at things such as drawing sketches of the solar system to scale, or just drawing any massive objects with tiny details. Of course, this app is also perfectly well suited for use as a normal canvas.
+            InfiniPaint is a collaborative, infinite space, infinite zoom, canvas note-taking/drawing app. Unlike many other infinite canvas apps, although there is a specific zoom-in level limit, there is no zoom-out limit. This means that this app is very good at things such as drawing sketches of the solar system to scale, or just drawing any massive objects with tiny details. Of course, this app is also perfectly well suited for use as a normal canvas.
         </p>
         <p>Features:</p>
         <ul>
@@ -64,13 +64,15 @@
                     <li>Lasso select tool added</li>
                     <li>Savefiles are compressed, leading to smaller files</li>
                     <li>Large network messages are compressed, leading to better online performance</li>
-                    <li>Can now embed and display SVG files on the canvas</li>
+                    <li>Can embed and display SVG files on the canvas</li>
+                    <li>Can display more raster image types: webp, wbmp</li>
                     <li>Selection can be modified:
                         <ul>
                             <li>Hold left shift to add to selection</li>
                             <li>Hold left alt to remove from selection</li>
                         </ul>
                     </li>
+                    <li>Can change canvas background color</li>
                     <li>Small visual changes</li>
                 </ul>
             </description>