Don't use lists in footnotes (#11378)

- Number the point sentences
- Use first, next and finally
- Replace .using Nix-style with with etc
- Replace it with build-depends
- Use code style for build-depends

Co-authored-by: Artem Pelenitsyn <a.pelenitsyn@gmail.com>

Author: philderbeast

doc/cabal-package-description-file.rst

@@ -3455,8 +3455,10 @@ a few options:
 .. rubric:: Footnotes
 
 .. [#old-style-build-tool-depends]
-   Some packages (ab)use :pkg-field:`build-depends` on old-style builds, but this has a few major drawbacks:
-
-   - using Nix-style builds it's considered an error if you depend on a exe-only package via build-depends: the solver will refuse it.
-   - it may or may not place the executable on ``PATH``.
-   - it does not ensure the correct version of the package is installed, so you might end up overwriting versions with each other.
+   Some packages (ab)use :pkg-field:`build-depends` on old-style builds, but
+   this has a few major drawbacks. First, with Nix-style builds it's considered
+   an error if you depend on a exe-only package via ``build-depends``: the
+   solver will refuse it.  Next, ``build-depends`` may or may not place the
+   executable on ``PATH``.  Finally, ``build-depends`` does not ensure the
+   correct version of the package is installed, so you might end up overwriting
+   versions with each other.