[3.0] [pt] Including intro.rst

Including missing file translated.
Update intro.rst
Clean up Configuration docs.

* Reduce fluff
* Add headings.
* Remove incorrect information.
Tighten up docs for routing.
Remove duplicate TOC entry.
Fix broken/wrong content
Inline TOC for components.
[fr] follow update-configuration
fix typo & remove 2 files in dev folder
Merge pull request #1792 from cakephp/update-configuration

Update configuration
[3.0] [pt] Create conventions.rst
[3.0] [pt] Create where-to-get-help.rst
[3.0] [pt] Create where-to-get-help.rst
Rename pt/where-to-get-help.rst to intro/cakephp-folder-structure.rst
Update conventions.rst
Merge pull request #1801 from andtxr/patch-7

[3.0] [pt] Create intro / cakephp-folder-structure.rst
Update where-to-get-help.rst
Update conventions.rst
Update intro.rst
Merge pull request #1791 from andtxr/patch-1

[3.0] [pt] Create intro.rst