Translation of installation instruction to English

[silkroadnomad]

The two installation instructions

• manual for linux https://github.com/Doichain/dapp/blob/master/doc/de/install-manual-linux.md
• via docker https://github.com/Doichain/dapp/blob/master/doc/de/install-docker.md

must be translated to English.

Please see https://bounties.doichain.org/ how to apply for Doichain bounties.