Translated
Translated
Updated after watching the vide lectures
Updated according to feedback
Updated according to feedback
Merge pull request #248 from jcarlosgarcia/index-cardinality

Completed translation of "14-Index cardinality" parts a and b. Resolves #241
Merge pull request #249 from jcarlosgarcia/index-selectivity

Completed translation of "15-Index selectivity" parts a and b. Resolves #242