Add extension to `csp.contribution.ts`

Adds the missing extension value for the CSP langugage in `csp.contribution.ts`

src/basic-languages/csp/csp.contribution.ts

@@ -10,7 +10,7 @@ declare var require: any;
 
 registerLanguage({
 	id: 'csp',
-	extensions: [],
+	extensions: ['.csp'],
 	aliases: ['CSP', 'csp'],
 	loader: () => {
 		if (AMD) {