fix(adventure): use existing convention for head and sprite syntax (#677)

Author: Privatech38

src/content/docs/adventure/minimessage/format.mdx

@@ -530,7 +530,7 @@ Kyori supports <pride:trans>trans rights</pride>!
 *(since v4.25.0)* Inserts a sprite.
 
 Tag
-  * `<sprite:[atlas]:<sprite>>`
+  * `<sprite[:atlas]:sprite>`
 
 Arguments
   * `atlas` the atlas to use, e.g. `minecraft:blocks`.
@@ -547,7 +547,7 @@ This item costs 10 x <sprite:"minecraft:items":item/porkchop>.
 *(since v4.25.0)* Inserts a player head.
 
 Tag
-  * `<head:<name|uuid|texture>:[outer_layer]>`
+  * `<head:name|uuid|texture[:outer_layer]>`
 
 Arguments
   * `name|uuid|texture` the name, UUID or path to the texture of the skin to use to draw the head.