Fix KDecoration2 API links
This fixes KDecoration2 links that were redirecting incorrectly as it's in the Plasma namespace.
Changes done:
'tags': 'https://api.kde.org/plasma/kdecoration/html/KDecoration2.tags',
'base_url': 'https://api.kde.org/kdecoration/html/' <-- wrong
'base_url': 'https://api.kde.org/plasma/kdecoration/html/' <-- correct
Edited by Thiago Sueto