chore: add missing BitVec names (#406)

Author: david-christiansen

Manual/BasicTypes/BitVec.lean

@@ -361,6 +361,8 @@ Because bitvectors are understood as two's complement numbers, addition, subtrac
 
 {docstring BitVec.uaddOverflow}
 
+{docstring BitVec.usubOverflow}
+
 ### Signed Operations
 
 {docstring BitVec.abs}
@@ -377,10 +379,14 @@ Because bitvectors are understood as two's complement numbers, addition, subtrac
 
 {docstring BitVec.saddOverflow}
 
+{docstring BitVec.ssubOverflow}
+
 ## Iteration
 
 {docstring BitVec.iunfoldr}
 
+{docstring BitVec.iunfoldr_replace}
+
 ## Proof Automation
 
 ### Bit Blasting