Section link anchor icon

[brandenchan]

• We used to have anchor links via icons for each section in the docs which made it easier to share the exact position of a page in a link
• It would be really helpful to have these
• c.f. This page where a link icon comes up when you hover near a section title

[fstau]

@brandenchan would you like to have control over which headlines get this anchor or should every headline get this and we just use the text of that headline to generate the link (e.g. "Language Modelling" -> "#language-modeling")?

[brandenchan]

In our docs, and tutorials, anything that is a level 1 or 2 headline should get this anchor I reckon (e.g. "# Document Store" or "## Elasticsearch Document Store"). Though one exception to this is the API docs where each class and class method should have an anchor. I believe these might be level 2 and 3 headlines.