refactor: restore shell script extensions

Without an extension, the shell script configuration in `.gitattribute` will not work.

tools/release.sh

@@ -37,7 +37,7 @@ help() {
   echo "  2. Merge the release branch into the default branch"
   echo
   echo "Usage:"
-  echo "  bash ./tools/release [options]"
+  echo "  bash $0 [options]"
   echo
   echo "Options:"
   echo "  --prepare           Preparation for release"

tools/test.sh

@@ -19,7 +19,7 @@ help() {
   echo
   echo "Usage:"
   echo
-  echo "   bash ./tools/test [options]"
+  echo "   bash $0 [options]"
   echo
   echo "Options:"
   echo '     -c, --config   "<config_a[,config_b[...]]>"    Specify config file(s)'