Fix typos mostly in comments, docs and test names (GH-15209)

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 770e0c4..4368bb5 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -3025,7 +3025,7 @@
         # Testing a str subclass used as dict key ..
 
         class cistr(str):
-            """Sublcass of str that computes __eq__ case-insensitively.
+            """Subclass of str that computes __eq__ case-insensitively.
 
             Also computes a hash code of the string in canonical form.
             """