docs: add tip command inside the docs

Signed-off-by: Vincenzo Palazzo <[email protected]>

Author: vincenzopalazzo

docs/docs-book/src/support-coffee.md

@@ -41,3 +41,25 @@ itself. With some craziness will be also possible to manage core lightning itsel
 
 Please if you feel that additional meta information needs to be specified open an issue 
 https://github.com/coffee-tools/coffee/issues
+
+## Tipping
+
+While there are possibility to tipping anything on lightning, there is any solution to tipping a core lightning plugin
+developer. So with coffee as developer you can define a BOLT 12 invoice that allow the developer of the plugin 
+to receive tips. So, the developer of the plugin should define a coffee manifest that specify the `tipping` info.
+
+An example can be:
+
+```yaml
+---
+plugin:
+  name: btcli4j
+  version: 0.0.1
+  lang: java
+  install: |
+    sh -C ./gradlew createRunnableScript
+  main: btcli4j-gen.sh
+tipping: 
+  bolt12: <bolt12 invoice>
+```
+

docs/docs-book/src/using-coffee.md

@@ -159,6 +159,15 @@ Additionally, if you wish to perform a verification of coffee without making any
 coffee nurse --verify
 ```
 _________
+### Tipping a plugin in Bitcoin
+
+> ✅ Implemented
+
+```
+coffee tip <plugin_name> <millisatoshi>
+```
+
+------
 ## Running coffee as a server
 
 To run Coffee as a server, you can use the `coffee_httpd` binary.