revert moving "creating packages" from Pkg.jl (#53509)

As mentioned in
#52102 (comment),
having this information be moved from Pkg to Base creates a quite
uncomfortable split between information about the package manager
between the Pkg docs and Base.

Pkg PR: JuliaLang/Pkg.jl#3818

(cherry picked from commit 3357d1b)

Author: KristofferC

doc/make.jl

@@ -193,7 +193,6 @@ BaseDocs = [
 StdlibDocs = [stdlib.targetfile for stdlib in STDLIB_DOCS]
 
 Tutorials = [
-    "tutorials/creating-packages.md",
     "tutorials/profile.md",
     "tutorials/external.md",
 ]