examples changed to things to do

Hi folks

As discussed last call we slightly changed the format of the examples, to
work with the heading  "aviod" and "use"
See examples
<https://docs.google.com/document/d/1sUlcUelA8mkom0jdeul_b7QEzqOc5_t4QJ863feVLJA/edit#heading=h.p2n8gjczio88>
.
we also filled them out a bit more so we have some statements of very
common things to use and avoid.
If you have time it is really worth reviewing and seeing if any important
cases are missed out.

All the best

lIsa