Add notice for conda package legacy labelling

Author: gforsyth

_notices/rsn0042.md

@@ -0,0 +1,60 @@
+---
+layout: notice
+parent: RAPIDS Support Notices
+grand_parent: RAPIDS Notices
+nav_exclude: true
+notice_type: rsn
+# Update meta-data for notice
+notice_id: 42 # should match notice number
+notice_pin: true # set to true to pin to notice page
+
+title: "Moving older RAPIDS conda packages to a `legacy` label"
+notice_author: RAPIDS Ops
+notice_status: Proposal
+notice_status_color: blue
+# 'notice_status' and 'notice_status_color' combinations:
+#   "Proposal" - "blue"
+#   "Completed" - "green"
+#   "Review" - "purple"
+#   "In Progress" - "yellow"
+#   "Closed" - "red"
+notice_topic: Platform Support Change
+notice_rapids_version: "<=v23.02"
+notice_created: 2025-01-27
+# 'notice_updated' should match 'notice_created' until an update is made
+notice_updated: 2025-01-27
+---
+
+## Overview
+
+RAPIDS will move certain older conda packages in the `rapidsai` conda channel
+under a new label: `legacy`. These packages will still be available by appending
+`--label legacy` to installation and search commands.
+
+By moving these packages out of the main portion of the channel, newer RAPIDS
+conda environments will be solvable with `strict_channel_priority`, speeding up
+environment solve times.
+
+All RAPIDS conda install commands for RAPIDS versions `v23.04+` will continue to
+work without any user intervention.
+
+This change will occur concurrently with the release of RAPIDS `v25.04`.
+
+
+## Impact
+
+RAPIDS environments installed using `conda` or `mamba`, for environments older
+than RAPIDS `v23.04` will fail to install unless `--label legacy` is appended to
+the installation command.
+
+e.g. if you are creating an environment like:
+
+```python
+mamba create -n rapids-23.02 rapids=23.02 python=3.10 'cuda-version>=11.4,<=11.8' -c rapidsai -c conda-forge -c nvidia
+```
+
+you will need to instead run 
+
+```python
+mamba create -n rapids-23.02 rapids=23.02 python=3.10 'cuda-version>=11.4,<=11.8' -c rapidsai -c conda-forge -c nvidia --label legacy
+```