update documentation on graphql-kotlin

[dariuszkuc]

Add documentation on graphql-kotlin (https://github.com/ExpediaGroup/graphql-kotlin) usage for creating reactive GraphQL server and http client.

[dariuszkuc]

FYI attempting to start gatsby from latest source didn't work for me due to the conflicting graphql versions

> npm list graphql
@0.0.0 /path/to/project/graphql.org
├─┬ [email protected]
│ ├─┬ [email protected]
│ │ └─┬ [email protected]
│ │   └── UNMET PEER DEPENDENCY [email protected] 
│ ├─┬ [email protected]
│ │ └── [email protected] 
│ └── UNMET PEER DEPENDENCY [email protected] 
└── [email protected] 

npm ERR! peer dep missing: graphql@^14.4.1, required by [email protected]
npm ERR! peer dep missing: graphql@^14.4.1, required by [email protected]
npm ERR! peer dep missing: graphql@^0.10.5 || ^0.11.3 || ^0.12.0 || ^0.13.0 || ^14.0.0, required by [email protected]

Downgrading graphql package to 14.7.0 worked locally.

[orta]

Yeah, we need to remove the npm instructions - good reminder.

Nice idea, having two different descriptions for the lib in client and server