Rework PrestaShop.gitignore

The previous file was made for PrestaShop maintainers it didn't suit PrestaShop user needs.

Prestashop.gitignore

-# Directories content
-cache/class_index.php
-cache/smarty/cache/*
-!cache/smarty/cache/index.php
-cache/smarty/compile/*
-!cache/smarty/compile/index.php
-cache/tcpdf/*
-!cache/tcpdf/index.php
+# Private files
+# The following files contain your database credentials and other personal data.
 
-config/xml/*.xml
-config/settings.inc.php
-
-log/*.log
+config/settings.*.php
 
-img/*
-!img/index.php
-!img/*/index.php
+# Cache, temp and generated files
+# The following files are generated by PrestaShop.
 
-tools/smarty*/cache/*.php
-!tools/smarty*/cache/index.php
-tools/smarty*/compile/*.php
-!tools/smarty*/compile/index.php
+admin-dev/autoupgrade/
+cache/
+config/xml/*.xml
+log/
+*sitemap.xml
+themes/*/cache/
+modules/*/config*.xml
 
-themes/default/cache/*.js
-themes/default/cache/*.css
+# Site content
+# The following folders contain product images, virtual products, CSV's, etc.
 
-# Ignore files on root directory
-robots.txt
-sitemap.xml
+admin-dev/backups/
+admin-dev/export/
+admin-dev/import/
+download/
+img/
+upload/