move docs, remove katex

bin/hydrooj.js

@@ -1,15 +1,18 @@
 #!/usr/bin/env node
 
+const { argv } = require('yargs');
 const hydro = require('../dist/loader');
 
+const ui = argv.ui || '@hydrooj/ui-default';
+
 try {
-    require.resolve('@hydrooj/ui-default');
+    require.resolve(ui);
 } catch (e) {
     console.error('Please also install @hydrooj/ui-default');
     process.exit(1);
 }
 
-hydro.addon('@hydrooj/ui-default');
+hydro.addon(ui);
 
 hydro.load().catch((e) => {
     console.error(e);