FakeSMTP's repo is read-only and hasn't been updated since 2016, so I removed it. The link to FakeEmail's repo was pointing at a fork that also hasn't been updated since 2016, so i changed the link to one that has more activity. Also smtp4dev has been moved to Github and works on Linux, so I updated its entry to reflect that.
* Update README.md
Added links to the recommended optional libraries.
Changed order of "Upgrading from 5.2" and "Legacy versions", i think this way is more logical to read.
Updated language quantity in the "Localization" section.
* Update README.md
Corrected review
* Update README.md
* Update phpmailer.lang-es.php
Added missing point to make grammatically correct and consistent with the other translations.