Add comments about travis test.

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/.travis.yml b/.travis.yml
index 3d735bb..2e9bdb4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -89,7 +89,9 @@
           packages:
           - gcc
       script:
-        # See above
+        # Do a manual build+test sequence rather than using all.sh, because
+        # there's no all.sh component that does what we want. We should set
+        # CFLAGS for arm64 host CC.
         - scripts/config.py full
         - scripts/config.py unset MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
         - scripts/config.py unset MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY
@@ -115,7 +117,9 @@
           - clang
           - gnutls-bin
       script:
-        # See above
+        # Do a manual build+test sequence rather than using all.sh, because
+        # there's no all.sh component that does what we want. We should set
+        # CFLAGS for arm64 host CC.
         - scripts/config.py full
         - scripts/config.py unset MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
         - scripts/config.py unset MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY
@@ -128,7 +132,6 @@
         - tests/scripts/travis-log-failure.sh
         - tests/context-info.sh
 
-
 after_failure:
 - tests/scripts/travis-log-failure.sh