doc/tutorials/basic: update hidden.md

Fix typo

Closes #72
cuelang/cue#72

GitOrigin-RevId: 327c31bb72631686adacd6bfd4292937897a2d9e
Change-Id: Ie61bab63df6e46174aa5dcdae51257b065d4fcdf
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2866
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: noelmcloughlin

doc/tutorial/basics/hidden.md

@@ -6,7 +6,7 @@ _References and Visibility_
 
 A non-quoted field name that starts with an underscore (`_`) is not
 emitted from the output.
-To includes fields in the configuration that start with an underscore
+To include fields in the configuration that start with an underscore
 put them in quotes.
 
 Quoted and non-quoted fields share the same namespace unless they start