docs/UPGRADING.md: Drop the note about OneShot stickability

OneShot has dropped the old stickability controls almost a year ago, and that's
already part of UPGRADING.md. Remove the note that they will be removed - they
already were.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

docs/UPGRADING.md

@@ -21,7 +21,6 @@ If any of this does not make sense to you, or you have trouble updating your .in
   + [Deprecated APIs and their replacements](#deprecated-apis-and-their-replacements)
     - [Removal of Layer.defaultLayer](#removal-of-layerdefaultlayer)
     - [More clarity in Layer method names](#more-clarity-in-layer-method-names)
-    - [Finer OneShot stickability control](#finer-oneshot-stickability-control)
     - [EEPROMKeymap mode](#eepromkeymap-mode)
     - [Source code and namespace rearrangement](#source-code-and-namespace-rearrangement)
 * [Removed APIs](#removed-apis)
@@ -499,10 +498,6 @@ the firmware to remain backwards compatible, however, these functions are deprec
 
 Also a new version of the onKeyswitchEvent-handler has been introduced. The old version is deprecated.
 
-### Finer OneShot stickability control
-
-The [OneShot plugin](doc/plugin/OneShot.md) has much improved stickability control. Instead of only being able to control if one-shot layers should be stickable too, or disabling the sticky feature in general, it is now possible to control stickiness on a per-key basis with the new `OneShot.enableStickability()` and `OneShot.disableStickablity()` methods. The old properties are still available, but will be removed by **2019-04-30**.
-
 ### EEPROMKeymap mode
 
 The [EEPROM-Keymap](doc/plugin/EEPROM-Keymap.md) plugin had its `setup()` method changed, the formerly optional `method` argument is now obsolete and unused. It can be safely removed. Supplying a second argument will continue to work until its scheduled removal by **2019-04-30**.