Validate-Keys config parameter missing in Enterprise 1.X documentation

[validate-keys](https://docs.influxdata.com/influxdb/v1/administration/config/#validate-keys) is present in OSS 1.X documentation, but missing from Enterprise 1.X documentation.

##### Relevant URLs
- [validate-keys](https://docs.influxdata.com/influxdb/v1/administration/config/#validate-keys) is present in OSS 1.X documentation, but missing from Enterprise 1.X documentation
