Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -67,7 +67,7 @@ Here's what you can do to help:
   - `nums` for arrays of numbers.
 - Use `()` if your function takes no arguments.
 - Use `_` if an argument inside some function (e.g. `Array.prototype.reduce()`) is not used anywhere in your code.
-- Specify default parameters for arguments, if necessary. It is preferred to put default parameters last unless you have pretty a good reason not to.
+- Specify default parameters for arguments, if necessary. It is preferred to put default parameters last unless you have a pretty good reason not to.
 - If your snippet's function takes variadic arguments, use `...args` (although in certain cases, it might be needed to use a different name).
 - If your snippet function's body is a single statement, omit the `return` keyword and use an expression instead.
 - Always use soft tabs (2 spaces), never hard tabs.