Correctly translate table captions in Czech (#63)

Adds missing translation for table caption in Czech language

Author: antoninkriz

lang/cs.css

@@ -2,3 +2,4 @@
 :lang(cs) .lemma::before { content: 'Lemma ' counter(theorem) '. ' !important; }
 :lang(cs) .proof::before { content: 'Důkaz. ' attr(title) !important; }
 :lang(cs) .definition::before { content: 'Definice ' counter(definition) '. ' !important; }
+:lang(cs) caption::before { content: 'Tabulka ' counter(caption) '. ' !important; }