Renaming to sports and adding triathlon related topic

Renaming the topic to `sports` as this one containes over 1,000 more repositories as `sport` on GitHub.
Adding the `triathlon` related topic.

Signed-off-by: Moonrise <[email protected]>

Author: PetitPotiron

topics/sport/index.md

@@ -0,0 +1,9 @@
+---
+display_name: Sports
+topic: sports
+aliases: sport
+short_description: Any physical activity or a game featuring skills or fitness
+related: cycling, soccer, football, badminton, volleyball, triathlon, fitness, yoga, running, swimming, tennis, basketball, handball, rowing, bodybuilding, rugby, hockey, wellbeing, health, olympics, paralympics, garmin, wahoo, strava, smartwatch
+wikipedia_url: https://en.wikipedia.org/wiki/Sport
+---
+Sports often consists of physical activities or a game that requires some skills or physical abilities. Sports can be teamsports as well as solo-sports, and they can be practiced indoor as well as outdoor. Practicing sports often improves overall health and mental wellness. While some people take parts to big events in order to compete agains each other, like the Olympics or the Paralympics, other people prefer to practice sports as a hobby.