Closes #11710: create "landing pages" (/library/package.html) for those packages…

Closes #11710: create "landing pages" (/library/package.html) for those packages that have no documented content themselves, e.g. "urllib" or "http".

Doc/library/concurrency.rst

@@ -15,6 +15,7 @@ multitasking) Here's an overview:
 
    threading.rst
    multiprocessing.rst
+   concurrent.rst
    concurrent.futures.rst
    subprocess.rst
    sched.rst

Doc/library/concurrent.rst

+The :mod:`concurrent` package
+=============================
+
+Currently, there is only one module in this package:
+
+* :mod:`concurrent.futures` -- Launching parallel tasks

Doc/library/html.rst

@@ -19,3 +19,10 @@ This module defines utilities to manipulate HTML.
    attribute value delimited by quotes, as in ``<a href="...">``.
 
    .. versionadded:: 3.2
+
+--------------
+
+Submodules in the ``html`` package are:
+
+* :mod:`html.parser` -- HTML/XHTML parser with lenient parsing mode
+* :mod:`html.entities` -- HTML entity definitions

Doc/library/http.rst

+:mod:`http` --- HTTP modules
+============================
+
+``http`` is a package that collects several modules for working with the
+HyperText Transfer Protocol:
+
+* :mod:`http.client` is a low-level HTTP protocol client; for high-level URL
+  opening use :mod:`urllib.request`
+* :mod:`http.server` contains basic HTTP server classes based on :mod:`socketserver`
+* :mod:`http.cookies` has utilities for implementing state management with cookies
+* :mod:`http.cookiejar` provides persistence of cookies

Doc/library/internet.rst

@@ -23,10 +23,12 @@ is currently supported on most popular platforms.  Here is an overview:
    cgi.rst
    cgitb.rst
    wsgiref.rst
+   urllib.rst
    urllib.request.rst
    urllib.parse.rst
    urllib.error.rst
    urllib.robotparser.rst
+   http.rst
    http.client.rst
    ftplib.rst
    poplib.rst
@@ -40,6 +42,7 @@ is currently supported on most popular platforms.  Here is an overview:
    http.server.rst
    http.cookies.rst
    http.cookiejar.rst
+   xmlrpc.rst
    xmlrpc.client.rst
    xmlrpc.server.rst
    ipaddress.rst

Doc/library/markup.rst

@@ -9,20 +9,13 @@ data markup.  This includes modules to work with the Standard Generalized Markup
 Language (SGML) and the Hypertext Markup Language (HTML), and several interfaces
 for working with the Extensible Markup Language (XML).
 
-It is important to note that modules in the :mod:`xml` package require that
-there be at least one SAX-compliant XML parser available. The Expat parser is
-included with Python, so the :mod:`xml.parsers.expat` module will always be
-available.
-
-The documentation for the :mod:`xml.dom` and :mod:`xml.sax` packages are the
-definition of the Python bindings for the DOM and SAX interfaces.
-
 
 .. toctree::
 
    html.rst
    html.parser.rst
    html.entities.rst
+   xml.rst
    xml.etree.elementtree.rst
    xml.dom.rst
    xml.dom.minidom.rst

Doc/library/urllib.rst

+:mod:`urllib` --- URL handling modules
+======================================
+
+``urllib`` is a package that collects several modules for working with URLs:
+
+* :mod:`urllib.request` for opening and reading URLs
+* :mod:`urllib.error` containing the exceptions raised by :mod:`urllib.request`
+* :mod:`urllib.parse` for parsing URLs
+* :mod:`urllib.robotparser` for parsing ``robots.txt`` files

Doc/library/xml.rst

+.. _xml:
+
+XML Processing Modules
+======================
+
+Python's interfaces for processing XML are grouped in the ``xml`` package.
+
+It is important to note that modules in the :mod:`xml` package require that
+there be at least one SAX-compliant XML parser available. The Expat parser is
+included with Python, so the :mod:`xml.parsers.expat` module will always be
+available.
+
+The documentation for the :mod:`xml.dom` and :mod:`xml.sax` packages are the
+definition of the Python bindings for the DOM and SAX interfaces.
+
+The XML handling submodules are:
+
+* :mod:`xml.etree.ElementTree`: the ElementTree API, a simple and lightweight
+
+..
+
+* :mod:`xml.dom`: the DOM API definition
+* :mod:`xml.dom.minidom`: a lightweight DOM implementation
+* :mod:`xml.dom.pulldom`: support for building partial DOM trees
+
+..
+
+* :mod:`xml.sax`: SAX2 base classes and convenience functions
+* :mod:`xml.parsers.expat`: the Expat parser binding

Doc/library/xmlrpc.rst

+:mod:`xmlrpc` --- XMLRPC server and client modules
+==================================================
+
+XML-RPC is a Remote Procedure Call method that uses XML passed via HTTP as a
+transport.  With it, a client can call methods with parameters on a remote
+server (the server is named by a URI) and get back structured data.
+
+``xmlrpc`` is a package that collects server and client modules implementing
+XML-RPC.  The modules are:
+
+* :mod:`xmlrpc.client`
+* :mod:`xmlrpc.server`