Add note about global pip command

Author: zooba

peps/pep-0773.rst

@@ -1177,6 +1177,19 @@ Debug binaries are no longer distributed, and all other optional features are
 included by default.
 
 
+Global pip command
+------------------
+
+Unlike the current Windows Store install, no global ``pip`` command is included
+(the traditional installer also does not include a global ``pip`` command,
+unless the options to modify ``PATH`` and to install pip are selected; the first
+of these is off by default). This impacts global installation of packages, which
+is already discouraged, but has no impact on activated virtual environments.
+
+The existing recommendation remains, which is to run ``python -m pip`` or
+``py -V:<TAG> -m pip`` to launch pip.
+
+
 Security Implications
 =====================