Update documentation

Author: yuanx749

Doc/library/mimetypes.rst

@@ -39,8 +39,8 @@ the information :func:`init` sets up.
    (e.g. :program:`compress` or :program:`gzip`). The encoding is suitable for use
    as a :mailheader:`Content-Encoding` header, **not** as a
    :mailheader:`Content-Transfer-Encoding` header. The mappings are table driven.
-   Encoding suffixes are case sensitive. Suffix mappings and type suffixes are
-   first tried case sensitively, then case insensitively.
+   Encoding suffixes are case-sensitive. Suffix mappings and type suffixes are
+   first tried case-sensitively, then case-insensitively.
 
    The optional *strict* argument is a flag specifying whether the list of known MIME types
    is limited to only the official types `registered with IANA
@@ -131,6 +131,8 @@ behavior of the module.
    is already known the extension will be added to the list of known extensions.
    Valid extensions are empty or start with a ``'.'``.
 
+   Registered lower-case extensions are matched case-insensitively.
+
    When *strict* is ``True`` (the default), the mapping will be added to the
    official MIME types, otherwise to the non-standard ones.
 
@@ -312,6 +314,8 @@ than one MIME-type database; it provides an interface similar to the one of the
       extension is already known, the new type will replace the old one. When the type
       is already known the extension will be added to the list of known extensions.
 
+      Registered lower-case extensions are matched case-insensitively.
+
       When *strict* is ``True`` (the default), the mapping will be added to the
       official MIME types, otherwise to the non-standard ones.
 

Lib/mimetypes.py

@@ -86,6 +86,9 @@ def add_type(self, type, ext, strict=True):
         is already known the extension will be added
         to the list of known extensions.
 
+        Registered lower-case extensions are matched
+        case-insensitively.
+
         If strict is true, information will be added to
         list of standard types, else to the list of non-standard
         types.
@@ -396,6 +399,9 @@ def add_type(type, ext, strict=True):
     is already known the extension will be added
     to the list of known extensions.
 
+    Registered lower-case extensions are matched
+    case-insensitively.
+
     If strict is true, information will be added to
     list of standard types, else to the list of non-standard
     types.