docs(option): fix embarassing typos

Co-authored-by: Christoph Knittel <christoph@knittel.cc>

Author: glennsl

src/Core__Option.resi

@@ -52,7 +52,7 @@ Option.some("foo") // Some("foo")
 let some: 'a => option<'a>
 
 /**
-`flat(value)` flattens a nested `option` value to a single level..
+`flat(value)` flattens a nested `option` value to a single level.
 
 ## Examples
 
@@ -90,7 +90,7 @@ Option.forEach(None, x => Console.log(x)) // returns ()
 let forEach: (option<'a>, 'a => unit) => unit
 
 /**
-`getExn(opt)` returns `value` is `Some(value)`, raises `Not_found` if `None`.
+`getExn(opt)` returns `value` if `Some(value)`, raises `Not_found` if `None`.
 
 ```rescript
 Option.getExn(Some(3)) // 3
@@ -127,7 +127,7 @@ Option.getUnsafe(Some(3)) == 3
 Option.getUnsafe(None) // Raises an error
 ```
 
-## Improtant
+## Important
 
 This is an unsafe operation, it assumes `value` is neither `None`, `Some(None))`, `Some(Some(None))` etc.
 */
@@ -306,7 +306,7 @@ cmp(None, None, clockCompare) // 0
 let cmp: (option<'a>, option<'b>, ('a, 'b) => int) => int
 
 /**
-`zip(a, b)` combines the values contained in `a` and `b` if both are `Some`, returns `None` otherwise..
+`zip(a, b)` combines the values contained in `a` and `b` if both are `Some`, returns `None` otherwise.
 
 ## Examples