Fix formatting and punctuation in Wikidata index

Fixed formatting issues and added punctuation.

Signed-off-by: Gabriel Lima Lopes <135924740+piratabrasileiro1@users.noreply.github.com>

Author: piratabrasileiro1

topics/wikidata/index.md

@@ -1,7 +1,8 @@
 ---
 display_name: Wikidata
-short_description: Wikidata is free and open knowledge base
+short_description: Wikidata is free and open knowledge base.
 related: wikipedia
 topic: wikidata
 ---
 Wikidata is a database by wikipedia created in 2012, used to give general information for the website and other projects. Wikidata acts as central storage for the structured data of its Wikimedia sister projects including Wikipedia, Wikivoyage, Wiktionary, Wikisource, and others.
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