Category Documentation fix

[dominikschnieper]

Q	A
Documentation Change	yes

Documentation for 20_Categories.md needs some changes.

config.yml
lucene_search:
categories: app_luceneserach_categories_service

services.yml:
app_luceneserach_categories_service:
class: AppBundle\LuceneSearch\Services\Categories

[solverat]

@dominikschnieper I think you fetched the wrong repo, right? If you're talking about the lucene search bundle, we could transfer this issue. Otherwise i'm going to close this one. Looking forward for your feedback.

[dominikschnieper]

@solverat oh, your correct. Please transfer this issue to lucene search bundle.