Support for Link Labels

I have fixed a few bugs recently caused by the fact that we changed the name of a Section, and as a consequence previous links included in other pages didn't work

Example

Page 1
Section 1

Page 2

Refer to page1.md#section-1

If that "Section 1" from Page 1 is changed in "New Section 1", the link page1.md#section-1 won't work anymore

Generally speaking, this issue is elegantly solved using labels, e.g. LaTeX uses this approach. In this approach a link label is defined, e.g.

Section 1\label{a_label_name}

and then the label name is used in other pages, when a link has to be created

When "Section 1" is renamed to "New Section 1" the label won't change, and as a consequence the link from Page 2 still works (as it makes use of the label)

It would be useful to see if something like this is supported from GitBook - as it would improve the way we work and quality of the documentation, avoiding broken links every time we change a section name

A possible mid-term objective

The issue does not name any repository files, tests, or entry points. First determine how the documentation system currently creates section anchors and resolves cross-page links; done means stable labels continue resolving after a section is renamed, with the supported syntax and affected behavior documented.