templates: updates to "learn more"

* Makes changes to external resources file, providing attributions where
  needed.  (addresses #66) (PR #163)
templates: s/analyze/analyse in "get started"

* Replaces `analyze` with `analyse` in "get started" page.
  (addresses #160) (PR #163)
templates: text corrections in VM Limitations

* Updates Limitations text in VM page.  (closes #156) (PR #166)