Merge pull request #623 from rsteube/doc-usage

doc: added usage

docs/src/SUMMARY.md

@@ -26,6 +26,7 @@
     - [Suppress](./carapace/action/suppress.md)
     - [Style](./carapace/action/style.md)
     - [Tag](./carapace/action/tag.md)
+    - [Usage](./carapace/action/usage.md)
   - [InvokedAction](./carapace/invokedAction.md)
     - [Filter](./carapace/invokedAction/filter.md)
     - [Merge](./carapace/invokedAction/merge.md)

docs/src/carapace/action/usage.md

@@ -0,0 +1,22 @@
+# Usage
+
+[`Usage`] sets the `usage` message.
+
+> `usage` is implicitly set by default with [`Flag.Usage`] for flag and [`Command.Use`] for positional arguments.
+
+```go
+carapace.ActionValues().Usage("explicit usage")
+````
+
+```json
+{
+  "Version": "unknown",
+  "Usage": "explicit usage",
+  "Nospace": "",
+  "RawValues": []
+}
+```
+
+[`Usage`]: https://pkg.go.dev/github.com/rsteube/carapace#Action.Usage
+[`Command.Use`]:https://pkg.go.dev/github.com/spf13/cobra#Command
+[`Flag.Usage`]:https://pkg.go.dev/github.com/spf13/pflag#Flag