[FLINK-16880] Add tools and template Dockerfiles to facilitate release workflow
-rw-r--r-- 7 .gitignore
-rw-r--r-- 11357 LICENSE
-rw-r--r-- 1852 README.md
-rwxr-xr-x 1718 add-version.sh
-rw-r--r-- 0 gpg_keys.txt
drwxr-xr-x - template