Update category.tpl

Small fix because it's not an array...
Merge pull request #1967 from Pronux/patch-1

[-] FO : wrong type use for category
[-] FO : Fix bug #PSCSX-2653, cols and rows in adresses
Merge branch 'release' of https://github.com/PrestaShop/PrestaShop into release
[-] BO : Fix #PSCSX-2575
[-] BO : Fix bug #PSCSX-2659, tax rule form
Merge pull request #1965 from AlexEven/release

// Controllers: wording
// Check if _ps_mode_dev_ is already defined
Merge branch 'release' of https://github.com/PrestaShop/PrestaShop into release
[-] BO : Fix bug #PSCSX-2681 #PSCSX-2575 , dnd inactive
[-] BO : Fix bug #PSCSX-2684, bad icon on adminshops
[-] Fo : Fix bug #PSCSX-2694, mail encoding
Merge branch 'release' of https://github.com/PrestaShop/PrestaShop into release
// AdminModulesPositionsController.php: wording