Update misc things

Author: wooorm

package.json

@@ -26,8 +26,9 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
   "type": "module",
-  "module": "./index.js",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
@@ -56,7 +57,6 @@
   },
   "xo": {
     "prettier": true,
-    "ignores": [],
     "rules": {
       "no-var": "off",
       "prefer-arrow-callback": "off"

readme.md

@@ -12,14 +12,15 @@
 
 ## Install
 
+This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
+Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
+
 [npm][]:
 
 ```sh
 npm install unist-util-position-from-estree
 ```
 
-Note that this package is ESM only: it must be imported instead of required.
-
 ## Use
 
 ```js
@@ -53,8 +54,7 @@ Yields:
 
 ## API
 
-`unist-util-position-from-estree` exports the following identifiers:
-[`positionFromEstree`](#positionfromestreenode).
+This package exports the following identifiers: `positionFromEstree`.
 There is no default export.
 
 ### `positionFromEstree(node)`