Update blog.rst

Typo in filename
Merge pull request #1579 from gmansilla/patch-2

Update blog.rst
Remove frivolous PDO note
Shorten and simplify the landing page.

Keep it short and sweet with all the same great links.
Merge pull request #1580 from bcrowe/3.0-pdo-note

3.0 - Remove frivolous PDO note
Update info regarding plugin naming and loading changes.
Added quotes around names in comments
Fixed typos etc.
Update auth.rst
Merge pull request #1582 from aleixfabra/patch-2

Update auth.rst
Fix formatting.
Fix eg. code.
Merge pull request #1581 from cakephp/3.0-plugin

Update info regarding plugin naming and loading changes.
Update entities.rst

Fixing typo.
Merge pull request #1583 from gmansilla/patch-2

Update entities.rst
Update blog article a bit.
Improved wording, fixed typos
Composer with capital C

https://getcomposer.org/doc/00-intro.md
Composer with capital C for other languages, too
Fixed/improved wording