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

Most fixes to Doc/ and Lib/ directories by Ville Skyttä.
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index f585ffc..e19df6e 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1627,7 +1627,7 @@
 #ifdef Py_USING_UNICODE
             if (PyUnicode_Check(item)) {
                 /* Defer to Unicode join.
-                 * CAUTION:  There's no gurantee that the
+                 * CAUTION:  There's no guarantee that the
                  * original sequence can be iterated over
                  * again, so we must pass seq here.
                  */