Fix regex pattern in schema to ensure valid subsection keys

Author: hawkeyexl

src/schema.js

@@ -186,7 +186,7 @@ export const schema = {
           description: "Object of subsections",
           type: "object",
           patternProperties: {
-            "^[A-Za-z0-9-_]+": {
+            "^[A-Za-z0-9-_]+$": {
               anyOf: [{ $ref: "#/definitions/section" }],
             },
           },