[PATCH] doc: add sunset clause for experimental tag

[Stephen Hemminger <stephen@networkplumber.org>]

The experimental tag is intended as temporary to avoid having
all of DPDK APIs as experimental and thereby rendering the
stable policy as worthless.

Add some wording into the existing policy in doc.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 doc/guides/contributing/abi_policy.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/doc/guides/contributing/abi_policy.rst b/doc/guides/contributing/abi_policy.rst
index 5fd405258592..fbf26ea24fd6 100644
--- a/doc/guides/contributing/abi_policy.rst
+++ b/doc/guides/contributing/abi_policy.rst
@@ -328,6 +328,16 @@ new APIs and start finding issues with them, new DPDK APIs will be automatically
 marked as ``experimental`` to allow for a period of stabilization before they
 become part of a tracked ABI version.
 
+The experimental tag has as limited lifetime (sunset provision).
+It is expected to be removed in a future release.
+The tag may be removed as soon as the second release with the new DPDK API.
+After one year, the API must be stable and tag removed unless an
+exception is approved by the technical board.
+
+For example, the symbol ``rte_flow_dev_dump`` was introduced
+in 20.02 release as ``experimental``. The tag could have been removed
+in 20.05 release, and should have been removed in 21.03 release.
+
 Note that marking an API as experimental is a multi step process.
 To mark an API as experimental, the symbols which are desired to be exported
 must be placed in an EXPERIMENTAL version block in the corresponding libraries'
-- 
2.42.0