* staking-miner: docker image
* renaming
* add doc
* fix readme
* remove the creation of home for the polkadot user
* new builder image for the staking-miner
* remove mentions of the polkadot binary and add env
* foc: fix doc
* fix typos and dictionnary
* doc + sync up the 2 images
* doc: fine tuning the doc
* doc: security warning