docs(ngBind): fix typo

Author: Michal Reichert

src/ng/directive/ngBind.js

@@ -12,7 +12,7 @@
  * Typically, you don't use `ngBind` directly, but instead you use the double curly markup like
  * `{{ expression }}` which is similar but less verbose.
  *
- * Once scenario in which the use of `ngBind` is preferred over `{{ expression }}` binding is when
+ * One scenario in which the use of `ngBind` is preferred over `{{ expression }}` binding is when
  * it's desirable to put bindings into template that is momentarily displayed by the browser in its
  * raw state before Angular compiles it. Since `ngBind` is an element attribute, it makes the
  * bindings invisible to the user while the page is loading.