Add examples to Schubert polynomials documentation

[trevorkarn]

Add examples to the documentation for Schubert polynomials.

CC: @tscrim @darijgr

Component: documentation

Keywords: gsoc2022 schubert-polynomial documentation

Author: Trevor K. Karn

Branch/Commit: 8fbcc34

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/34370

[trevorkarn]

New commits:

c2adcea

Add examples to SchubertPolynomials

[trevorkarn]

Commit: c2adcea

[trevorkarn]

Branch: u/tkarn/schubert-34370

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

5861650

Fix typo

[sagetrac-git]

Changed commit from c2adcea to 5861650

[tscrim]

comment:3

Please get out of the habit of writing lines like this:

+In Sage, they are modeled in the :class:`SchubertPolynomial_class`. Instances of
+this class can be created by creating an instance ``X`` of a Schubert polynomial
+ring using the constructor :func:`SchubertPolynomialRing`. 

They are useless as you have the examples and are already at the code (and technical regarding implementation details).

\\Bold{Z} -> \ZZ (only one \ as the string block is marked r).

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

8fbcc34

Fix reviewer comments

[sagetrac-git]

Changed commit from 5861650 to 8fbcc34

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:5

Thanks. LGTM.

[vbraun]

Changed branch from u/tkarn/schubert-34370 to 8fbcc34