Add title to ide/extraenv.json (#556)

Author: ddecrulle

onyxia-api/src/main/resources/schemas/ide/extraenv.json

@@ -1,9 +1,11 @@
 {
     "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "Environment variables",
     "description": "environment variables available within your service",
     "type": "array",
     "default": [],
     "items": {
+      "title": "environment variable",
       "type": "object",
       "properties": {
         "name": {