chore(documentation.yaml): add Metaprogramming in Lean 4#752

Vierkantor wants to merge 1 commit intolean4leanprover-community/leanprover-community.github.io:lean4from

add-metaprogramming-in-lean4leanprover-community/leanprover-community.github.io:add-metaprogramming-in-lean4Copy head branch name to clipboard