[DOC][TUTO] Merge fixes for quick-start step3/4 according to truffle/ganache changes

[rcoscali]

What

• Change steps 3&4 according to truffle/ganache updates

Why

• Because of issue Re organize menus #6 on rsksmart/truffle-integration repo, truffle and ganache have to be used in the last release
• Step2 have been changed accordingly then now step3 & step4
• Add resume at top of each page to be consistent accross tuto
• Fix some minor inconsistencies in miscellaneous places

Refs

• Issue#6 on rsksmart/truffle-integration repo: Issue with Ganache installation #Step 2 in Getting Started truffle-integration#6
• PR#7 on rsksmart/truffle-integration repo: Fix for #Issue6: ganache installation issue truffle-integration#7
• Modified Step1 tuto page: https://github.com/rcoscali/devportal/blob/patch-1/_quick-start/step1-install-rsk-local-node.md
• Modified Step2 tuto page: https://github.com/rcoscali/devportal/blob/patch-1/_quick-start/step2-install-truffle-and-ganache.md
• Modified Step3 tuto page: https://github.com/rcoscali/devportal/blob/rcoscali-patch-1/_quick-start/step3-edit-smart-contract.md
• Modified Step4 tuto page: https://github.com/rcoscali/devportal/blob/rcoscali-patch-1/_quick-start/step4-compile-and-deploy.md