Update text vendors to vendor on How to Define and Install Dependencies section.
Merge pull request #489 from frankperez87/composer-typo-fix

Update text vendors to vendor
Fix highlighter consistency

- in some places php would not be highlighted as the `<?php` tag was missing
- in one place there was a duplicate `<?php` tage
- replaced `bash` with `console` for better highlighting
- ensured all console snippets are wrapped within highlighting code
- wrapped ini examples in highlighting code