Prepare to release 2.1.1

Packages have received security updates in the last 2 commits:

- 1dd1630
- 8a06d98

For details, see:

- #31
- #32

package.json

@@ -1,6 +1,6 @@
 {
   "name": "mdast-util-from-adf",
-  "version": "2.1.0",
+  "version": "2.1.1",
   "description": "Convert from Atlassian Document Format to Markdown Abstract Syntax Tree",
   "license": "MIT",
   "author": {