more examples for the source block

website/pages/docs/from-1.5/blocks/source.mdx

@@ -14,8 +14,30 @@ The top-level `source` block defines reusable builder configuration blocks:
 
 `@include 'from-1.5/sources/example-block.mdx'`
 
-Build-level [`source` blocks](/docs/from-1.5/blocks/build/source) allows you to
-specifically set source fields at the moment of using them.
+You can start builders by refering to those source blocks form a [`build`
+block](/docs/from-1.5/blocks/build), for example :
+
+```hcl
+build {
+  source = [
+    # Here Packer will use a default ami_name when saving the image.
+    "sources.amazon-ebs.example",
+    "sources.amazon-ebs.foo",
+  ]
+}
+```
+
+The build-level [`source` block](/docs/from-1.5/blocks/build/source) allows to 
+set specific source fields.
+
+```hcl
+build {
+  source "sources.amazon-ebs.example" {
+    # Here Packer will use the provided ami_name instead of defaulting it.
+    ami_name = "specific"
+  }
+}
+```
 
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