Base: Fix a typo

Author: https://github.com/bugaevc
Commit: https://github.com/SerenityOS/serenity/commit/983e541584e
Pull-request: https://github.com/SerenityOS/serenity/pull/2114

Base/usr/share/man/man2/unveil.md

@@ -17,7 +17,7 @@ the file system the calling process is allowed to access.
 
 A process that has not made any `unveil()` calls is allowed to access the whole
 filesystem (subject to the regular permission checks). A process that has made
-one or more `unveil()` calls cannot access any paths excpet those that were
+one or more `unveil()` calls cannot access any paths except those that were
 explicitly unveiled.
 
 Calling `unveil()` allows the process to access the given `path`, which must be