[PATCH v3] doc: add deprecation for restrictions in telemetry naming

[Bruce Richardson <bruce.richardson@intel.com>]

Following discussion on-list [1], we will look to limited the allowed
characters in names for items in telemetry. This will simplify the
escaping needed for json output, or any future output formats. The lists
will initially be minimal, since expansion to allow more characters can
be done without affecting compatibility, while reducing the set cannot.

[1] http://inbox.dpdk.org/dev/20220623164245.561371-1-bruce.richardson@intel.com/#r

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: David Marchand <david.marchand@redhat.com>
---
 doc/guides/rel_notes/deprecation.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 4e5b23c53d..6ef93758d4 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -119,6 +119,13 @@ Deprecation Notices
 * metrics: The function ``rte_metrics_init`` will have a non-void return
   in order to notify errors instead of calling ``rte_exit``.
 
+* telemetry: The allowed characters in names for dictionary values will be limited to
+  alphanumeric characters and a small subset of additional printable characters.
+  This will ensure that all dictionary parameter names can be output without escaping
+  in JSON - or in any future output format used. Names for the telemetry commands will
+  be similarly limited. The parameters for telemetry commands are unaffected by this
+  change.
+
 * raw/ioat: The ``ioat`` rawdev driver has been deprecated, since it's
   functionality is provided through the new ``dmadev`` infrastructure.
   To continue to use hardware previously supported by the ``ioat`` rawdev driver,
-- 
2.34.1