Improve grammar in the import system reference documentation (GH-18209)


Replaced the period with a comma.

Automerge-Triggered-By: @Mariatta
(cherry picked from commit d47d0c8e9f2ca0f9f5d1bf0b35006a9a4d5ca684)

Co-authored-by: Bonifacio de Oliveira <bonifacio.segundo@gmail.com>
diff --git a/Doc/reference/import.rst b/Doc/reference/import.rst
index c6f6d03..1c98aab 100644
--- a/Doc/reference/import.rst
+++ b/Doc/reference/import.rst
@@ -855,7 +855,7 @@
 This spec will always have "loader" set (with one exception).
 
 To indicate to the import machinery that the spec represents a namespace
-:term:`portion`. the path entry finder sets "loader" on the spec to
+:term:`portion`, the path entry finder sets "loader" on the spec to
 ``None`` and "submodule_search_locations" to a list containing the
 portion.