Addd WA index 58 (#172)

Released/Gen 8/Wild Area Events/readme.md

@@ -57,6 +57,7 @@
 - [Index 055](Index%20055) - [Wild Area Event #34](#Wild-Area-Event-34-February-2021)
 - [Index 056](Index%20056) - [Wild Area Event #36](#Wild-Area-Event-36-The-Return-of-Gigantamax-Milcery)
 - [Index 057](Index%20057) - [Wild Area Event #34](#Wild-Area-Event-34-February-2021)
+- [Index 058](Index%20058) - [Wild Area Event #37](#Wild-Area-Event-34-Pokemon-Day-2021-Gigantamax-Pikachu)
 
 ## Instructions
 To import these files into your save, use PKHeX's block importing function. Our [tutorial](https://projectpokemon.org/tutorials/save-editing/gen-8_157/block-editing-r106/) should guide you through it.
@@ -307,4 +308,9 @@ This is a Wild Area event held by Sword and Shield. All slots of this event host
 At time of writing, there is no other way to obtain Ribbon and Star sweets in-game, without Mystery Gift or Max Raid updates.
 Thus this max raid update is one of the only times players can obtain those items.
 
-This event also has an increased chance of landing a Shiny Milcery; players have a 2% chance of landing on a guaranteed Shiny, only at the 5 star tier. 
+This event also has an increased chance of landing a Shiny Milcery; players have a 2% chance of landing on a guaranteed Shiny, only at the 5 star tier. 
+
+## [Wild Area Event #37: Pokemon Day 2021 Gigantamax Pikachu](https://projectpokemon.org/home/files/file/4428-wild-area-event-37-pok%C3%A9mon-day-2021-gigantamax-pikachu/)
+This is a Wild Area event held by Sword and Shield. This Max Raid event was distributed to players to commemorate the Pokémon Day 2021.
+This Max Raid event adds Gigantamax Pikachu as a possible encounter into the previous Max Raid encounters.
+This event also has an increased chance of landing a Shiny Gigantamax Pikachu; players have a 2% chance of landing on a guaranteed Shiny, only at the 5 star tier.