Fix typo in build script (mainly for triggering CI).

build.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # build.sh checks if docker image with same sha256 exists remotely.
-# if exists, do nothing, if not, build the image
+# if exists, do nothing, if not, build the image.
 
 commit_sha="${DRONE_COMMIT_SHA}"
 image_path="${REGISTRY}${REGISTRY_PROJECT}"