Rollup merge of rust-lang#26788 - tshepang:not-exclamation-marks, r=steveklabnik

The sentences are also so short that they don't need periods at the end

Author: steveklabnik

src/doc/reference.md

@@ -3344,8 +3344,8 @@ is often called ‘unit’ or ‘the unit type’.
 
 Rust has two different types for a list of items:
 
-* `[T; N]`, an 'array'.
-* `&[T]`, a 'slice'.
+* `[T; N]`, an 'array'
+* `&[T]`, a 'slice'
 
 An array has a fixed size, and can be allocated on either the stack or the
 heap.