LogBook: Add link to logbook in sidebar

You need to update the wikipage at URL /wiki/sidebar. Two cases:

• page doesn't exist yet: create it, fill it with a link #### Sidebar\n{{child_pages(Wiki)}}
• page exists already:
  • macro is already there: do nothing
  • macro is not there: insert the link at the very beginning of the page

Refs https://redmine.teklia.com/issues/6533