Add index of all DNR examples to all DNR examples (#527)

dnr-block-only/README.md

@@ -40,3 +40,9 @@ specific to Manifest Version 3.
 To create a MV2 version of the extension, modify `manifest.json` as follows:
 
 - Set `manifest_version` to 2.
+
+# Index of DNR examples
+
+- [dnr-block-only](https://github.com/mdn/webextensions-examples/tree/main/dnr-block-only) (this example)
+- [dnr-dynamic-with-options](https://github.com/mdn/webextensions-examples/tree/main/dnr-dynamic-with-options)
+- [dnr-redirect-url](https://github.com/mdn/webextensions-examples/tree/main/dnr-redirect-url)

dnr-dynamic-with-options/README.md

@@ -103,3 +103,9 @@ To create a MV2 version of the extension, modify `manifest.json` as follows:
      the same value as `optional_host_permissions` for the reasons explained in
      the previous section. The latter is MV3-only and can be removed from a MV2
      manifest.
+
+# Index of DNR examples
+
+- [dnr-block-only](https://github.com/mdn/webextensions-examples/tree/main/dnr-block-only)
+- [dnr-dynamic-with-options](https://github.com/mdn/webextensions-examples/tree/main/dnr-dynamic-with-options) (this example)
+- [dnr-redirect-url](https://github.com/mdn/webextensions-examples/tree/main/dnr-redirect-url)

dnr-redirect-url/README.md

@@ -62,3 +62,9 @@ As an alternative to renaming `host_permissions` to `optional_permissions`,
 add the match patterns in the `host_permissions` array to the
 `permissions` key of the MV2 manifest. Then the user does not need to opt in to
 the host permission, and the extension works immediately after installation.
+
+# Index of DNR examples
+
+- [dnr-block-only](https://github.com/mdn/webextensions-examples/tree/main/dnr-block-only)
+- [dnr-dynamic-with-options](https://github.com/mdn/webextensions-examples/tree/main/dnr-dynamic-with-options)
+- [dnr-redirect-url](https://github.com/mdn/webextensions-examples/tree/main/dnr-redirect-url) (this example)