None of the Tilemap components have docs associated with them. If you have the docs installed, none of the components show a link to docs in the inspector. If you don't have the docs installed, the link is shown but leads to a 404 page. Affects all components associated with Tilemap:

Grid
Tilemap
Tilemap Collider
Tilemap Renderer

Tested in 2017.2.0f3, 2017.3.0b11, 2018.1.0a6

1. Open attached project
2. Open main.scene
3. Select the Tilemap GameObject
4. Look at the Tilemap components attached to the GameObject in the Inspector
5. None of the Tilemap components have links to docs