Add Ionic 3 into the titles of the old docs

**Is your feature request related to a problem? Please describe.**
Google has abstracted away the url with breadcrumbs and both the Ionic 3 and Ionic 4 documents all look the same now in the SERPs:


**Describe the solution you'd like**
Add Ionic 3 to the page titles of the old docs. Consider adding Ionic 4 into the new docs, although with with Ionic 5 coming up fast it seems that it just needs a way of differentiating the old content.

**Describe alternatives you've considered**
I have considered zero alternatives.

**Additional context**
Screenshot above. 5 points for anyone who can tell me which points at which? :)

Start by locating the old documentation pages and their current titles. Update those titles to include Ionic 3 and verify the rendered titles; whether to add Ionic 4 is left as a consideration in the issue.

Written by the indexing model from the issue text.