Write release notes for v5.4.1

doc/release-notes.md

@@ -4,3 +4,29 @@ release-notes at release time)
 Notable changes
 ===============
 
+`allowdeprecated` in `zcash.conf`
+---------------------------------
+
+In v5.0.0 a [feature deprecation framework](https://zcash.github.io/zcash/user/deprecation.html)
+was released, to enable `zcashd` features to be formally deprecated and removed:
+
+- In stage 1, a feature is marked as deprecated, but otherwise left as-is. It
+  remains in this stage for at least 18 weeks.
+- In stage 2, the feature is default-disabled, but can be re-enabled with the
+  `-allowdeprecated` config option. It remains in this stage for at least 18
+  weeks.
+- Finally, the feature is removed - either entirely, or (e.g. in the case of RPC
+  methods that were inherited from Bitcoin Core) with a "tombstone" left to
+  inform users of the removal (and what to use instead if applicable).
+
+Config options can be specified either as a `zcashd` argument (`-option=value`)
+or in `zcash.conf` (as a `option=value` line). However, due to a bug in the
+implementation, `allowdeprecated=feature` lines in `zcash.conf` were ignored.
+The bug went unnoticed until v5.4.0, in which the first group of features moved
+from stage 1 to stage 2. This hotfix releases fixes the bug.
+
+Fixed RPC blocking and wallet view lag on reindex
+-------------------------------------------------
+
+The known issue reported in the v5.4.0 release notes has been fixed.
+