bip3: Require technical soundness

Co-authored-by: [email protected]

Author: murchandamus

bip-0003.md

@@ -491,7 +491,7 @@ For each new BIP pull request that comes in, an editor checks the following:
 * Motivation, Rationale, and Backward Compatibility have been addressed
 * Specification provides sufficient detail for implementation
 * The defined Layer and Type headers must be correctly assigned for the given specification
-* The BIP is ready: it is comprehensible, technically feasible, and all aspects are addressed as necessary
+* The BIP is ready: it is comprehensible, technically feasible and sound, and all aspects are addressed as necessary
 
 Editors do NOT evaluate whether the proposal is likely to be adopted.