bash: refresh page: add here-doc example and parameter expansion examples

[EmilyGraceSeville7cf]

closes #95

[EmilyGraceSeville7cf]

bash variables use curly braces, not angle brackets. For example echo ${variable}

Yeah, but it's not a bash syntax, it's placeholder syntax that used over bash syntax. :) I suggested to stick to shell syntax only to @chrisallenlane, but he declined this idea.

[edgester]

@EmilySeville7cfg Thanks for clarifying. I think the placeholder syntax is confusing in this case, but @chrisallenlane has the final word.

[EmilyGraceSeville7cf]

I am closing this PR to make project maintainer pay attention for it.