Add notrunc docstrings

Author: lkdvos

src/interface/truncation.jl

@@ -34,6 +34,13 @@ See also [`notrunc()`](@ref).
 """
 struct NoTruncation <: TruncationStrategy end
 
+"""
+    notrunc()
+
+Truncation strategy that does nothing, and keeps all the values.
+"""
+notrunc() = NoTruncation()
+
 """
     TruncationKeepSorted(howmany::Int, by::Function, rev::Bool)