docs (#149): enforce consistent quotes

Co-authored-by: Natalia Tepluhina <tarya.se@gmail.com>

src/guide/migration/attribute-coercion.md

@@ -23,7 +23,7 @@ In 2.x, we had the following strategies for coercing `v-bind` values:
 
 - For "[enumerated attributes](https://github.com/vuejs/vue/blob/bad3c326a3f8b8e0d3bcf07917dc0adf97c32351/src/platforms/web/util/attrs.js#L20)" (currently `contenteditable`, `draggable` and `spellcheck`), Vue tries to [coerce](https://github.com/vuejs/vue/blob/bad3c326a3f8b8e0d3bcf07917dc0adf97c32351/src/platforms/web/util/attrs.js#L24-L31) them to string (with special treatment for `contenteditable` for now, to fix [vuejs/vue#9397](https://github.com/vuejs/vue/issues/9397)).
 
-- For other attributes, we remove “falsy” values (`undefined`, `null`, or `false`) and set other values as-is (see [here](https://github.com/vuejs/vue/blob/bad3c326a3f8b8e0d3bcf07917dc0adf97c32351/src/platforms/web/runtime/modules/attrs.js#L92-L113)).
+- For other attributes, we remove "falsy" values (`undefined`, `null`, or `false`) and set other values as-is (see [here](https://github.com/vuejs/vue/blob/bad3c326a3f8b8e0d3bcf07917dc0adf97c32351/src/platforms/web/runtime/modules/attrs.js#L92-L113)).
 
 The following table describes how Vue coerce "enumerated attributes" differently with normal non-boolean attributes: