Close #19406: Initial implementation of ensurepip

Patch by Donald Stufft and Nick Coghlan
diff --git a/Doc/library/index.rst b/Doc/library/index.rst
index 1b25c6e..81289a5 100644
--- a/Doc/library/index.rst
+++ b/Doc/library/index.rst
@@ -65,6 +65,7 @@
    tk.rst
    development.rst
    debug.rst
+   distribution.rst
    python.rst
    custominterp.rst
    modules.rst