staking-miner: docker images (#3682)

* 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

polkadot/scripts/gitlab/lingua.dic

@@ -155,6 +155,7 @@ natively
 NFA
 NFT/SM
 nonces
+NPoS
 no_std
 NTB
 offboard/DMSG