Add excel solutions (#976)

README.md

@@ -30,6 +30,7 @@ This is a collection of awesome resources related to the yearly
     * [Elixir](#elixir)
     * [Elm](#elm)
     * [Erlang](#erlang)
+    * [Excel](#excel)
     * [F#](#f)
     * [Go](#go)
     * [Groovy](#groovy)
@@ -254,6 +255,12 @@ Read [CONTRIBUTING.md](/CONTRIBUTING.md) to learn how to add your own repos.
 
 * [hypothermic/advent-of-code-2021](https://github.com/hypothermic/advent-of-code-2021) ![Last Commit on GitHub](https://img.shields.io/badge/last%20commit-2021--12--02-brightgreen)
 
+#### Excel
+ 
+*Solutions to AoC in Excel.*
+
+ * [detrang1301/adventofcode-2021-excel](https://github.com/detrang1301/adventofcode-2021-excel)
+
 #### F#
 
 *Solutions to AoC in F#.*