PEP 610: specification will live on packaging.python.org (#1282)

Also add note about reproducibility

As suggested by Nick Coghlan at https://discuss.python.org/t/draft-pep-recording-the-origin-of-distributions-installed-from-direct-url-references/1535/41?u=sbidoul

* PEP 610: amending must be done by writing a new PEP

As suggested by NIck Coghlan

pep-0610.rst

@@ -212,7 +212,7 @@ as a dictionary with the following keys:
 
 - A ``vcs`` key (type ``string``) MUST be present, containing the name of the VCS
   (i.e. one of ``git``, ``hg``, ``bzr``, ``svn``). Other VCS's SHOULD be registered by
-  amending this PEP. 
+  writing a PEP to amend this specification. 
   The ``url`` value MUST be compatible with the corresponding VCS,
   so an installer can hand it off without transformation to a
   checkout/download command of the VCS.
@@ -282,7 +282,7 @@ on how to use the ``vcs``, ``requested_revision``, and other fields of
 ``vcs_info``; and in
 some cases additional VCS-specific fields.
 Tools MAY support other VCS's although it is RECOMMENDED to register
-them by amending this PEP. The ``vcs`` field SHOULD be the command name
+them by writing a PEP to amend this specification. The ``vcs`` field SHOULD be the command name
 (lowercased). Additional fields that would be necessary to
 support such VCS SHOULD be prefixed with the VCS command name.
 
@@ -478,6 +478,13 @@ Use cases
   the ``tag`` value if present, as it has immutable semantics.
   Tools MAY choose another approach, depending on the needs of their users.
 
+  Note the initial iteration of this PEP does not attempt to make environments
+  that include editable installs or installs from local directories
+  reproducible, but it does attempt to make them readily identifiable. By
+  locating the local project directory via the ``url`` and ``dir_info`` fields
+  of this specification, tools can implement any strategy that fits their use
+  cases.
+
 Backwards Compatibility
 =======================