Make TL eligibility health-check more actionable (facebook#5085)

Summary:
Pull Request resolved: facebook#5085

I was very excited to see this warning in the UI:

{F1987030629}

But it also seemed insufficiently actionable for either users or agents. I think a vague mention of the UI is ok even though this is going into OSS; what do folks think?

NOTE: Also a thought: should we be saying "Transfer Learning Eligibilty" or "Meta-Learning Eligibility"?

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: mgarrard, eonofrey

Differential Revision: D97489418

fbshipit-source-id: b90a0eab1445ad10683baeb917fae81aa9b077d3

Author: Lena Kashtelyan

ax/analysis/healthcheck/transfer_learning_analysis.py

@@ -175,7 +175,9 @@ def compute(
             "Using data from unrelated experiments can lead to negative "
             "transfer, which may hurt "
             "optimization performance. Review the overlapping parameters "
-            "before enabling transfer learning."
+            "before enabling transfer learning. If using the UI, 'Learn from "
+            "Related Experiments' button is likely available for use; "
+            "otherwise, use `Client.add_transferable_experiment`."
         )
 
         return TransferLearningAnalysisCard(