Clarify that tools may override ordering/selection

Clarify that tools may override ordering/selection

Signed-off-by: Michał Górny <mgorny@quansight.com>
Co-authored-by: Ralf Gommers <ralf.gommers@gmail.com>

Author: mgorny

peps/pep-0825.rst

@@ -379,7 +379,8 @@ MUST obtain an ordered list of compatible features, and for every
 feature, an ordered list of compatible values. The method of obtaining
 these lists will be defined in a subsequent PEP.
 
-The ordering MUST be performed equivalent to the following algorithm:
+The default ordering MUST be performed equivalent to the following
+algorithm:
 
 1. Construct the ordered list of namespaces by copying the value of the
    ``default-priorities.namespace`` key from `index-level metadata`_.
@@ -447,6 +448,11 @@ after the null variant. Multiple wheels with the same variant property
 set (and multiple non-variant wheels) MUST then be ordered according to
 their platform compatibility tags.
 
+The tools MAY provide options to override the default ordering, for
+example by specifying a preference for specific namespaces, features
+or properties. The tools MAY also provide options to exclude specific
+variants, or to select a particular variant.
+
 Alternatively, the sort algorithm for variant wheels could be described
 using the following pseudocode. For simplicity, this code does not
 account for non-variant wheels or tags.