Trac #34477: one-letter typo in docstring of Sets.ParentMethods.algebra()

In the docstring of
`sage.categories.sets_cat.Sets.ParentMethods.algebra()`, `self` is "a
parent `S`". However, this parent is erroneously called `G` at one
point.

URL: https://trac.sagemath.org/34477
Reported by: gh-DaveWitteMorris
Ticket author(s): Dave Morris
Reviewer(s): Kwankyu Lee

Author: Release Manager

src/sage/categories/sets_cat.py

@@ -1616,7 +1616,7 @@ def algebra(self, base_ring, category=None, **kwds):
               of `S`, or ``None``
 
             This returns the space of formal linear combinations of
-            elements of `G` with coefficients in `R`, endowed with
+            elements of `S` with coefficients in `K`, endowed with
             whatever structure can be induced from that of `S`.
             See the documentation of
             :mod:`sage.categories.algebra_functor` for details.