add man pages for shell commands and implement mkdir, ping, matrix, and about commands

src/shell/commands/rm.ts

@@ -21,4 +21,8 @@ export class rm implements IShellCommand {
         this.syscall.deleteFile(filename);
         return `Removed ${filename}`;
     }
+
+    getManPage(): string {
+        return "rm - remove files or directories";
+    }
 }