package/gtest: fix explanation typo

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit e9beedc3d4151dfaca41922e98d0a6a9f0ce690e)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gtest/gtest.mk

@@ -18,7 +18,7 @@ GTEST_CPE_ID_PRODUCT = google_test
 # gtest.
 # So, force to build gtest as a static library.
 #
-# For further details, refer to the explaination given in the README file from
+# For further details, refer to the explanation given in the README file from
 # the gtest sources.
 GTEST_CONF_OPTS = -DBUILD_SHARED_LIBS=OFF