`deploying` page lacks information for handling fails

[sonicfromnewyoke]

Problem

during the renovation #747 of deploying program page a couple of important steps were omitted:

• recovering of failed deploys with solana-keygen recover -o ./target/deploy/buffer-keypair.json. Also ,i guess, it can be added CLI Command Reference
• how to build program for different loader versions (v3 vs v4)

those steps are pretty important for newcomers, so i'd prefer to have them included in the docs

Potential Solution

return those 2 paragraphs back