Condition in tests but not in task description

I have added the condition that was not included in the task description but was included in the tests.
also __proto__ is  a non standard property.
It maybe good to mention as the first test usually fails just because it is not mentioned to ignore the properties from the prototype chain.

subjects/pick-omit/README.md

@@ -7,6 +7,7 @@ Create two functions which taken an object and a string or array of strings. The
 - `omit`: contains only those keys which do not match the string, or do not appear in the array of strings.
 
 > Those functions are pure and must not modify the given object
+> It should ignore properties from the prototype chain
 
 ### Notions