Update README.md

Author: grimpirate

README.md

@@ -1,4 +1,11 @@
 # SVGWall
 SVG Wallpaper Utility for Xorg
 
+    Usage: SVGWall-x86_64.AppImage [-chuV] [-s=FILE]
+      -c, --check      Check for SVGWall-x86_64.AppImage update and exit.
+      -h, --help       Show this help message and exit.
+      -s, --svg=FILE   SVG file
+      -u, --update     Update SVGWall-x86_64.AppImage and exit.
+      -V, --version    Print version information and exit.
+
 ![Screenshot](https://raw.githubusercontent.com/grimpirate/SVGWall/main/screenshot.png "SVGWall")