Make .addSection fully declarative

docs/usage/bullet-points.md

@@ -6,21 +6,23 @@
 To make a bullet point, simply make a paragraph into a bullet point:
 
 ```ts
-doc.addSection({
-    children: [
-        new Paragraph({
-            text: "Bullet points",
-            bullet: {
-            level: 0 //How deep you want the bullet to be
-          }
-        }),
-        new Paragraph({
-            text: "Are awesome",
-            bullet: {
-            level: 0
-          }
-        })
-    ],
+const doc = new Document({
+    sections: [{
+        children: [
+            new Paragraph({
+                text: "Bullet points",
+                bullet: {
+                level: 0 //How deep you want the bullet to be
+            }
+            }),
+            new Paragraph({
+                text: "Are awesome",
+                bullet: {
+                level: 0
+            }
+            })
+        ],
+    }];
 });
 ```