Fix grammar, typos and markup in documentation and code comments

* Indent versionchanged at method level, not class level
* Mark up ``--help`` to avoid generating an en dash
* Use forward slash in Unix command line with a dollar sign ($) prompt
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 46c99b5..89b0798 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -1012,7 +1012,7 @@
                                                            errors);
         if (self->encoder == NULL)
             goto error;
-        /* Get the normalized named of the codec */
+        /* Get the normalized name of the codec */
         res = _PyObject_GetAttrId(codec_info, &PyId_name);
         if (res == NULL) {
             if (PyErr_ExceptionMatches(PyExc_AttributeError))