interpolate variables within markdown admonitions

[clarkevans]

Variable interpolation does not seem to be happening within markdown admonitions.

julia> using Markdown

julia> v = "Hello"
"Hello"

julia> md"""
       !!! note
           $v
       $v
       """
  │ Note
  │
  │:v

"Hello"

julia> versioninfo()
Julia Version 1.10.0
Commit 3120989f39b (2023-12-25 18:01 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 16 × Intel(R) Xeon(R) E-2278GE CPU @ 3.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, skylake)
  Threads: 1 on 16 virtual cores