Docs: `search`: regex / operators clarification

## Overview
I was reading through https://incatools.github.io/ontology-access-kit/intro/tutorial01.html#search and also compared against https://incatools.github.io/ontology-access-kit/cli.html#runoak-search, and in the former, there are some syntax that you can use, like `^`, and `~`, as well as `/` for full regex, but that is not mentioned in the CLI command docs. Just wondering if: (i) it should be, (ii) if what I mentioned here was an exhaustive list, or if there are more.

As I look through the docs more, I see that the guide is naturally more thorough than the CLI reference. I think it makes sense for the guide to have more examples and exposition, but I do think things like options and syntax probably ought to be in the CLI reference as well.

Compare the search syntax in the tutorial at intro/tutorial01.html#search with the CLI reference at cli.html#runoak-search. Check which operators and regex forms are documented in each, then update the CLI reference so its options and syntax are covered consistently; done means the relevant search syntax is clearly documented there.

Written by the indexing model from the issue text.