chore: initial gomark plugin (#1678)

chore: initial gomark folder

plugin/gomark/ast/ast.go

@@ -0,0 +1,19 @@
+package ast
+
+type Node struct {
+	Type     string
+	Text     string
+	Children []*Node
+}
+
+type Document struct {
+	Nodes []*Node
+}
+
+func NewDocument() *Document {
+	return &Document{}
+}
+
+func (d *Document) AddNode(node *Node) {
+	d.Nodes = append(d.Nodes, node)
+}