add some comments about safety

Author: rob-p

content/docs/get-started/2.values.md

@@ -12,7 +12,13 @@ when failures occur. Eliminating these modes of failure in omics development and
 analyses is one of the primary reasons the project was created.
 
 To that end, correctness should be considered the highest priority of crates in the
-`rust-seq` stack—**even at the cost of performance**.
+`rust-seq` stack—**even at the cost of performance**.  
+
+In situations where performance is critical, developers should provide both a _safe_ 
+and _unsafe_ interface, clearly documenting the pre-requisites for the _unsafe_ interface 
+at the API level. Likewise, any `unsafe` code should be explicity documented (in the code) 
+with a comment beginning with the token `SAFETY:`, that explicitly describes why the code 
+in the unsafe block is expected to operate correctly and not invoke undefined behavior.
 
 ## Performant