Minor argument name changes

Author: nblumhardt

README.md

@@ -189,7 +189,7 @@ calling a function will be undefined if:
 
 | Function                        | Description                                                                                                                                                                                                                   |
 |:--------------------------------|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `Coalesce(p0, p1, [..pN])`      | Returns the first defined, non-null argument.                                                                                                                                                                                 |
+| `Coalesce(a0, a1, [..aN])`      | Returns the first defined, non-null argument.                                                                                                                                                                                 |
 | `Concat(s0, s1, [..sN])`        | Concatenate two or more strings.                                                                                                                                                                                              |
 | `Contains(s, p)`                | Tests whether the string `s` contains the substring `p`.                                                                                                                                                                      |
 | `ElementAt(x, i)`               | Retrieves a property of `x` by name `i`, or array element of `x` by numeric index `i`.                                                                                                                                        |