Add assembly renders to Upright microscope instructions

The Upright microscope instructions lack the correct renders for mounting the optics and the condenser.
The Upright instructions can also be based more closely on the main inverted instructions (#301 (closed)), using the GitBuilding include_text function (so this merge request replaces !329 (closed))

• Build renders of mounting the upright condenser (in the mount optics section)
• Update instructions to use the condenser mounting renders (mount_optics_upright<n>.png)
• Build renders for mounting the upright z-axis (in the mount illumination section)
• Update instructions to use the upright z-axis renders (in the mount illumination section new page)
• Build renders for mounting the upright optics module (new section)
• Add instruction page for mounting the upright optics module (new page)
• Add completed microscope page in the instructions
• Add prepare upright z-axis renders and replace photos with the renders
• Add renders for the assembled upright z-axis actuator
• Add renders for the upright z-axis motor assembled
• Add the new foot cap to the instructions and the list of parts to print

Scope creep:

• Review and update the pointers to Forum and Gitlab
• Add images/renders to each microscope type on the index page

closes: #367 (closed), #301 (closed)