doc: fix minor embedded struct typo (vlang#20678)

doc/docs.md

@@ -2672,7 +2672,7 @@ Button{
 ```
 
 Unlike inheritance, you cannot type cast between structs and embedded structs
-(the embedding struct can also has its own fields, and it can also embed multiple structs).
+(the embedding struct can also have its own fields, and it can also embed multiple structs).
 
 If you need to access embedded structs directly, use an explicit reference like `button.Size`.