tutorial: try to clarify the 'rings' section

[jhpalmieri]

The section in the tutorial on rings can be confusing to people who aren't familiar with them, and since this precedes the material on matrices (for example), people wanting to know how to solve linear equations might be thrown off. This patch attempts to remedy this, at least partially.

This patch depends on the scripts patches at #6572 -- without them, many of the doctests here will not actually be run.

If this patch is merged, then we should open up a ticket to do the same thing to the French version of the tutorial.

Component: documentation

Author: John Palmieri

Reviewer: Mike Hansen

Merged: sage-4.2.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/7148

[jhpalmieri]

Attachment: trac_7148-tutorial-rings.patch.gz

[mwhansen]

comment:3

Looks good to me.

[mwhansen]

Reviewer: Mike Hansen

[mwhansen]

Attachment: trac_7148-tutorial-rings.2.patch.gz

[mwhansen]

Merged: sage-4.2.alpha0

[mwhansen]

comment:4

I had to update the patch to take care of a change from #7007.