add example plugin with documentation

plugins/example-plugin.cmd.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/vladimirvivien/gosh/api"
+)
+
+// Make sure to replace `exampleCmd` with
+// what ever you want, but make sure it
+// does not clash with existing plugins,
+
+// # MULTIPLE COMMANDS CAN BE DECLARED IN
+// # THE SAME PLUGIN, see testcmd.go for
+// # an example
+
+type exampleCmd string
+
+// for plugins that dont contain a command to
+// load, all lines marked with //OP are optional
+// if your plugin adds a command, please fille these out
+func (t exampleCmd) Name() string      { return string(t) }                //OP
+func (t exampleCmd) Usage() string     { return `example` }                //OP
+func (t exampleCmd) ShortDesc() string { return `description of example` } //OP
+func (t exampleCmd) LongDesc() string  { return t.ShortDesc() }            //OP
+func (t exampleCmd) Exec(ctx context.Context, args []string) (context.Context, error) {
+
+	// Put your custom programming here, make sure to
+	// accept and parse the args variable if you need
+	// to!
+
+	return ctx, nil
+}
+
+type exampleCmds struct{}
+
+func (t *exampleCmds) Init(ctx context.Context) error {
+	out := ctx.Value("gosh.stdout").(io.Writer)
+
+	// If you want something to happen when the module
+	// loads, put it here,
+
+	fmt.Fprintln(out, "example module loaded OK")
+	return nil
+}
+
+func (t *exampleCmds) Registry() map[string]api.Command {
+	return map[string]api.Command{
+		"example": exampleCmd("example"), //OP
+	}
+}
+
+var Commands exampleCmds
+
+// If your plugin needs extra functions, declare
+// them down here to call upon, or import their
+// library.