kbuild: fix a couple of typos in Documentation

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 6f8c1ca..84725b7 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -65,7 +65,7 @@
 Specify an optional fixed part of the binutils filename.
 CROSS_COMPILE can be a part of the filename or the full path.
 
-CROSS_COMPILE is also used for ccache is some setups.
+CROSS_COMPILE is also used for ccache in some setups.
 
 CF
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