doc: spelling error changes

Fixed multiple spelling errors.

Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Carlos E. Garcia <carlos@cgarcia.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/robust-futexes.txt b/Documentation/robust-futexes.txt
index 0a9446a..af6fce2 100644
--- a/Documentation/robust-futexes.txt
+++ b/Documentation/robust-futexes.txt
@@ -210,7 +210,7 @@
 tested the new glibc code (on x86_64 and i386), and it works for his
 robust-mutex testcases.
 
-All other architectures should build just fine too - but they wont have
+All other architectures should build just fine too - but they won't have
 the new syscalls yet.
 
 Architectures need to implement the new futex_atomic_cmpxchg_inatomic()