Yarn test fails due to flow error

Going through the guide and I got a flow error running `yarn test`. See:
 verekia#221

The solution is to add:

```
[ignore]
.*/node_modules/eslint-plugin-jsx-a11y/*
```

I propose to add this to the guide so others won't have this issue.

tutorial/02-babel-es6-eslint-flow-jest-husky.md

@@ -245,6 +245,9 @@ I know this is a lot to take in, so take a minute to think about it. I'm still a
 ```flowconfig
 [options]
 suppress_comment= \\(.\\|\n\\)*\\flow-disable-next-line
+
+[ignore]
+.*/node_modules/eslint-plugin-jsx-a11y/*
 ```
 
 This is a little utility that we set up to make Flow ignore any warning detected on the next line. You would use it like this, similarly to `eslint-disable`: