docs: fix typo

docs/WorkflowGuidelines.md

@@ -165,7 +165,7 @@
         * Do not use edge-values to denote absence of value. Example: use null (`Nullable<DateTime>`) instead of `DateTime.MinValue`.
         * Use Option types instead of Nullable ones if your language provides it (e.g. if you're using F# instead of C#).
         * Do not use `undefined` which is a pitfall from JavaScript (the fact that it has two kinds of null values is a defect in
-        its design). As we're using TypeScript we should be able to avoid the uglyness of JavaScript.
+        its design). As we're using TypeScript we should be able to avoid the ugliness of JavaScript.
 
         Example (with bad practice):
         ```typescript