Fix documentation about stereographic viewing

[kcrisman]

In two of the PREP tutorials

• http://doc.sagemath.org/html/en/prep/Symbolics-and-Basic-Plotting.html#basic-3d-plotting
• http://doc.sagemath.org/html/en/prep/Advanced-2DPlotting.html#vector-fields
  there is mention of 3d glasses viewing

(right-click on the plot and select “Style” and “Stereographic”)

but this only works with jmol. One should modify these appropriately to include viewer='jmol'. Unless threejs supports this? But I believe not.

Component: documentation

Issue created by migration from https://trac.sagemath.org/ticket/28802

[embray]

comment:1

Ticket retargeted after milestone closed

[mkoeppe]

comment:2

Moving tickets to milestone sage-9.2 based on a review of last modification date, branch status, and severity.

[mkoeppe]

comment:4

Moving to 9.4, as 9.3 has been released.