tour: correct typo

Change-Id: I14f0317c1f6c36aa922c43eab45a7bc4dd698142
Reviewed-on: https://go-review.googlesource.com/c/website/+/394314
Reviewed-by: Eli Bendersky‎ <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Run-TryBot: Eli Bendersky‎ <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Trust: Eli Bendersky <[email protected]>

Author: enocom

_content/tour/generics.article

@@ -25,7 +25,7 @@ for any type that supports comparison.
 * Generic types
 
 In addition to generic functions, Go also supports generic types. A type can
-be parameterized with a type paremeter, which could be useful for implementing
+be parameterized with a type parameter, which could be useful for implementing
 generic data structures.
 
 This example demonstrates a simple type declaration for a singly-linked list