Issue #27076: Doc, comment and test function name spelling fixes

Most fixes to Doc/ and Lib/ directories by Ville Skyttä.
diff --git a/Lib/lib2to3/patcomp.py b/Lib/lib2to3/patcomp.py
index 093e5f9..d31a9da 100644
--- a/Lib/lib2to3/patcomp.py
+++ b/Lib/lib2to3/patcomp.py
@@ -3,7 +3,7 @@
 
 """Pattern compiler.
 
-The grammer is taken from PatternGrammar.txt.
+The grammar is taken from PatternGrammar.txt.
 
 The compiler compiles a pattern to a pytree.*Pattern instance.
 """