Update _index.md - an unofficial Loki client added (#6312)

I would like to add mjaron-tinyloki-java to unofficial Loki clients.
It is standalone small library without any dependencies. It may be an alternative to other libraries which use many dependencies and require more configuration to send logs.

docs/sources/clients/_index.md

@@ -73,5 +73,6 @@ when using or writing a third-party client.
 - [NLog-Targets-Loki](https://github.com/corentinaltepe/nlog.loki) (C#)
 - [loki-logback-appender](https://github.com/loki4j/loki-logback-appender) (Java)
 - [Log4j2 appender for Loki](https://github.com/tkowalcz/tjahzi) (Java)
+- [mjaron-tinyloki-java](https://github.com/mjfryc/mjaron-tinyloki-java) (Java)
 - [LokiLogger.jl](https://github.com/JuliaLogging/LokiLogger.jl) (Julia)
 - [winston-loki](https://github.com/JaniAnttonen/winston-loki) (JS)