Clear out v5.5.0 release notes

This enables PRs that have release notes to be merged in parallel to the
RC process.

doc/release-notes.md

@@ -4,83 +4,4 @@ release-notes at release time)
 Notable changes
 ===============
 
-RPC Changes
------------
 
-- `getdeprecationinfo` has several changes:
-  - It now returns additional information about currently deprecated and
-    disabled features.
-  - A new `end_of_service` object that contains both the block height for
-    end-of-service and the estimated time that the end-of-service halt is
-    expected to occur. Note that this height is just an approximation and
-    will change over time as the end-of-service block height approaches,
-    due to the variability in block times. The
-    `end_of_service` object is intended to replace the `deprecationheight`
-    field; see the [Deprecations](#deprecations) section for additional detail.
-  - This RPC method was previously only available for mainnet nodes; it is now
-    also available for testnet and regtest nodes, in which case it does not
-    return end-of-service halt information (as testnet and regtest nodes do not
-    have an end-of-service halt feature.)
-- Several `z_sendmany`, `z_shieldcoinbase` and `z_mergetoaddress` failures have
-  moved from synchronous to asynchronous, so while you should already be
-  checking the async operation status, there are now more cases that may trigger
-  failure at that stage.
-- The `AllowRevealedRecipients` privacy policy is now required in order to choose a
-  transparent change address for a transaction. This will only occur when the wallet
-  is unable to construct the transaction without selecting funds from the transparent
-  pool, so the impact of this change is that for such transactions, the user must specify
-  `AllowFullyTransparent`.
-- The `z_shieldcoinbase` and `z_mergetoaddress` RPC methods now support an
-  optional privacy policy.
-- The `estimatepriority` RPC call has been removed.
-- The `priority_delta` argument to the `prioritisetransaction` RPC call now has
-  no effect and must be set to a dummy value (0 or null).
-
-Changes to Transaction Fee Selection
-------------------------------------
-
-- The `-mintxfee` and `-sendfreetransactions` options have been removed. These
-  options used to instruct the wallet's legacy transaction creation APIs
-  (`sendtoaddress`, `sendmany`, and `fundrawtransaction`) to increase fees to
-  this limit and to use a zero fee for "small" transactions that spend "old"
-  inputs, respectively. They will now cause a warning on node startup if used.
-
-Changes to Block Template Construction
---------------------------------------
-
-We now use a new block template construction algorithm documented in
-[ZIP 317](https://zips.z.cash/zip-0317#recommended-algorithm-for-block-template-construction).
-
-- This algorithm no longer favours transactions that were previously considered
-  "high priority" because they spent older inputs. The `-blockprioritysize` config
-  option, which configured the portion of the block reserved for these transactions,
-  has been removed and will now cause a warning if used.
-- The `-blockminsize` option, which configured the size of a portion of the block
-  to be filled regardless of transaction fees or priority, has also been removed
-  and will cause a warning if used.
-- A `-blockunpaidactionlimit` option has been added to control the limit on
-  "unpaid actions" that will be accepted in a block for transactions paying less
-  than the ZIP 317 fee. This defaults to 50.
-
-Removal of Priority Estimation
-------------------------------
-
-- Estimation of "priority" needed for a transaction to be included within a target
-  number of blocks, and the associated `estimatepriority` RPC call, have been
-  removed. The format for `fee_estimates.dat` has also changed to no longer save
-  these priority estimates. It will automatically be converted to the new format
-  which is not readable by prior versions of the software. The `-txconfirmtarget`
-  config option is now obsolete and has also been removed. It will cause a
-  warning if used.
-
-[Deprecations](https://zcash.github.io/zcash/user/deprecation.html)
---------------
-
-The following features have been deprecated, but remain available by default.
-These features may be disabled by setting `-allowdeprecated=none`. 18 weeks
-after this release, these features will be disabled by default and the following
-flags to `-allowdeprecated` will be required to permit their continued use:
-
-- `deprecationinfo_deprecationheight`: The `deprecationheight` field of
-  `getdeprecationinfo` has been deprecated and replaced by the `end_of_service`
-  object.