chore: Typo on README - "One NAT Gateway per subnet" section (#917)

Author: altmas5

README.md

@@ -85,7 +85,7 @@ If both `single_nat_gateway` and `one_nat_gateway_per_az` are set to `true`, the
 
 ### One NAT Gateway per subnet (default)
 
-By default, the module will determine the number of NAT Gateways to create based on the the `max()` of the private subnet lists (`database_subnets`, `elasticache_subnets`, `private_subnets`, and `redshift_subnets`). The module **does not** take into account the number of `intra_subnets`, since the latter are designed to have no Internet access via NAT Gateway. For example, if your configuration looks like the following:
+By default, the module will determine the number of NAT Gateways to create based on the `max()` of the private subnet lists (`database_subnets`, `elasticache_subnets`, `private_subnets`, and `redshift_subnets`). The module **does not** take into account the number of `intra_subnets`, since the latter are designed to have no Internet access via NAT Gateway. For example, if your configuration looks like the following:
 
 ```hcl
 database_subnets    = ["10.0.21.0/24", "10.0.22.0/24"]