add 8.6.0 alpha release notes (#19173)

# Overview



Replacing Josh's placeholder with the 8.6.0 alpha release notes. 

## Test Plan and Hands on Testing



## Risk assessment

low.

Author: emilyburghardt

api/release-notes.md

@@ -10,7 +10,14 @@ By installing and using Opentrons software, you agree to the Opentrons End-User
 
 ## Opentrons Robot Software Changes in 8.6.0
 
-### TODO
+Welcome to the v8.6.0 release of the Opentrons robot software! This release adds support for the Flex Stacker Module, along with other new features and improvements.
+
+### New Features 
+
+- Automate labware storage with the Flex Stacker Module. Use new commands like `retrieve()` and `store()` to move well plates, reservoirs, or Flex tip racks to and from the Stacker during a protocol. 
+- This release adds support for the Opentrons Flex 96-Channel Pipette (1–200 μL) to transfer as little as 1 µL in a protocol. 
+- Control individual robot motors, like the gantry, extension mount, or gripper, with new  commands.  
+
 
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app-shell/build/release-notes.md

@@ -10,7 +10,17 @@ By installing and using Opentrons software, you agree to the Opentrons End-User
 
 ## Opentrons App Changes in 8.6.0
 
-### TODO
+Welcome to the v8.6.0 release of the Opentrons App! This release adds support for the Flex Stacker Module, as well as other improvements.
+
+### New Features
+
+- Automate labware storage with the Flex Stacker Module. Store additional well plates, reservoirs, or Flex tip racks to move onto the deck during a protocol, increasing workflow throughput.
+
+### Improvements
+
+- Choose from three Opentrons-verified liquid classes to optimize liquid handling in quick transfers.
+- Easily tell your tip racks apart during run setup. Colored tip racks now appear in the app to match different tip volume ranges.
+- Improvements to Labware Position Check include new prompts to apply offsets before a protocol run.
 
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