Documentation: fix kbuild typos and wording

Fixed some typos and wording.

Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 634c625..0d8addb 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -40,15 +40,15 @@
 modules.
 The directory can be specified in several ways:
 1) Use "M=..." on the command line
-2) Environmnet variable KBUILD_EXTMOD
-3) Environmnet variable SUBDIRS
+2) Environment variable KBUILD_EXTMOD
+3) Environment variable SUBDIRS
 The possibilities are listed in the order they take precedence.
 Using "M=..." will always override the others.
 
 KBUILD_OUTPUT
 --------------------------------------------------
 Specify the output directory when building the kernel.
-The output directory can also be specificed using "O=...".
+The output directory can also be specified using "O=...".
 Setting "O=..." takes precedence over KBUILD_OUTPUT.
 
 ARCH
@@ -90,7 +90,7 @@
     $3 - kernel map file
     $4 - default install path (use root directory if blank)
 
-The implmentation of "make install" is architecture specific
+The implementation of "make install" is architecture specific
 and it may differ from the above.
 
 INSTALLKERNEL is provided to enable the possibility to