DOC MAINT: Whitespace cleanup in documentation.

src/doc/extension/references.rst

@@ -23,11 +23,11 @@ the basic structure of the module should look like
        // Has to be called ``resolve`` and has to take exactly one
        // string parameter: the id of the referenced entity.
        this.resolve = async function (id) {
-	   /*
-	    * find the string that the reference should be resolved to,
-	    * e.g., from the value of the entity's properties.
-	    */
-	   return {"text": new_reference_text}
+           /*
+            * find the string that the reference should be resolved to,
+            * e.g., from the value of the entity's properties.
+            */
+           return {"text": new_reference_text}
        }
    }