fix spelling mistake

docs/building-a-realm/realm-examples/foo721.gno.md

@@ -152,7 +152,7 @@ func TransferFrom(from, to users.AddressOrName, tid grc721.TokenID) {
 Other functions are defined in the grc721 specification, each with the following roles.
 
 * `BalanceOf`: Returns the number of NFTs owned by an address.
-* `OwnerOf`: Chekcs the owner address of a token, specified by its `id`.
+* `OwnerOf`: Checks the owner address of a token, specified by its `id`.
 * `IsApprovedForAll`: Checks if all tokens of the `owner` has been approved for the `operator`.
 * `GetApproved`: Checks the address of the operator that's been approved of a token, specified by its `id`.
 * `Approve`: Approves a token owned by the `caller` to [a ](#user-content-fn-1)[^1]user. The token is specified by its `id`.