Installing contracts: update the naming convention from deploy to transaction

[sczembor]

What does this PR fix/introduce?

• update naming convention from Deploy to Transaction, sender to signer
• update the casper-client commands

Checklist

(Delete any that aren't relevant)

• [x] Docs are successfully building - yarn install && yarn run build.
• [x] For new internal links I used relative file paths (with .md extension) - e.g. ../../faq/faq-general.md - instead of introducing absolute file path, or relative/absolute URL.
• [x] All external links have been verified with yarn run check:externals.
• [x] My changes follow the Casper docs style guidelines.

Reviewers

@ACStoneCL