add documentation regarding the configuration

Signed-off-by: Augustin Husson <husson.augustin@gmail.com>

Author: Nexucis

README.md

@@ -62,6 +62,8 @@ The following Language Clients have been tested with this language server. More
 
 Feel free to reach out if you want to use it with another Editor/Tool.
 
+Reading this [documentation](./doc/developing_editor.md) can help you in your work
+
 ### VS Code
 
 There exists a VS Code extension based on this language server: <https://github.com/slrtbtfs/vscode-prometheus>
@@ -100,3 +102,11 @@ The Vim command `:YcmDebugInfo` gives status information and points to logfiles.
 
 1. Install package `LSP`, `LSP-promql` via `Package Control`.
 2. Follow the [installation instruction](https://github.com/nevill/lsp-promql#installation).
+
+## Contributing
+
+Refer to [CONTRIBUTING.md](./CONTRIBUTING.md)
+
+## License
+
+Apache License 2.0, see [LICENSE](./LICENSE).

doc/developing_editor.md

@@ -0,0 +1,30 @@
+Development of new client editor
+=============================
+
+This documentation will give you some tips to help when you are going to support the promql-server in a new editor.
+
+## Config
+There is two different config used by the promql-server. 
+
+### YAML configuration (cold configuration)
+The first one is a classic yaml file which can be used to customize the server when it is starting. It has the following structure:
+
+```yaml
+activate_rpc_log: false # It's a boolean in order to activate or deactivate the rpc log. It's deactivated by default
+log_format: "text" # The format of the log printed. Possible value: json, text. Default value: "text"
+prometheus_url: "http://localhost:9090" # the HTTP URL of the prometheus server.
+rest_api_port: 8080 # When set, the server will be started as an HTTP server. Default value: 0
+```
+
+### JSON configuration (hot configuration)
+There is a second configuration which is used only at the runtime.
+
+```json
+{
+  "promql": {
+    "url": "http://localhost:9090" # the HTTP URL of the prometheus server.
+  }
+}
+```
+
+This configuration will be watched thanks to the method implemented `DidChangeConfiguration`