add uninstalling eosio.cdt after manual installation

Merge pull request #434 from EOSIO/docs/ubuntu-16-delisting

[2.1.x] Delisted Ubuntu 16.04

fix misspelled command in eosio helm tutorial :doc

Merge pull request #272 from EOSIO/develop

Develop -> Master

Merge branch 'develop'

Merge pull request #255 from EOSIO/develop

Develop to Master

Merge pull request #252 from EOSIO/develop

Develop to Master

Merge pull request #237 from EOSIO/duncand0nuts-patch-1

Remove the duplicated EOSlime entry

Hotfix: fix link to SimpleAssets tool