Add some additional docs for webpack 2 usage.

Hello, you may add the following note for webpack 2 usage. Please add my github name as a contributor to the package if you decide to include this in your docs.

---

Note that ‘with’ that is deprecated in es6. For webpack 2 usage, you must pass an option in your query strict=true or _with=false that will disable with in the ejs package.

Examples: strict=true

import tmpl1 from '!!../?strict=true!./template.ejs';
import tmpl2 from '!!../?delimiter=?&strict=true!./template2.ejs';
import tmpl3 from '!!../?strict=true!./subdir/parent.ejs';

_with=false

import tmpl1 from '!!../?_with=false!./template.ejs';
import tmpl2 from '!!../?delimiter=?&_with=false!./template2.ejs';
import tmpl3 from '!!../?_with=false!./subdir/parent.ejs';

Template examples:

You will need to refer to your vars from the locals object when with has been disabled as illustrated below:

Hello, <%=locals.noun%>!

<? for(var key in locals.hobbies) { var hobby = locals.hobbies[key]; -?>
  I like {{=hobby}}.
<? } ?>

child: <%= locals.foo %>

[bazilio91]

kinda rotten, reopen if needed.

[neginbasiri]

@AndreiSoroka Do you know how to get webpack watch changes for include files?