Replacing only the first occurance of # Unreleased

Author: hiranya911

createReleaseTarball.sh

@@ -92,7 +92,7 @@ echo
 #  UPDATE CHANGELOG.md  #
 #########################
 echo "[INFO] Updating version number in CHANGELOG.md to ${VERSION_WITHOUT_RC}..."
-sed -i '' -e s/"# Unreleased"/"# v${VERSION_WITHOUT_RC}"/ CHANGELOG.md
+sed -i '' -e "1 s/# Unreleased/# v${VERSION_WITHOUT_RC}/" CHANGELOG.md
 echo -e "# Unrelased\n\n-\n" | cat - CHANGELOG.md > TEMP_CHANGELOG.md
 mv TEMP_CHANGELOG.md CHANGELOG.md