[doc] Removed unecessary dependency

doc/contributing.rst

@@ -47,11 +47,9 @@ Additional dependencies
 -----------------------
 * `ocamlformat <https://github.com/ocaml-ppx/ocamlformat>`_ is a formatter for
   OCaml code. It must be installed with the version specified in the
-  `.ocamlformat` file at the root of the directory
-* `ocp-indent <https://github.com/OCamlPro/ocp-indent>`_ helps properly
-  indenting OCaml code
-* a `python3` interpreter version 3.9 of higher is required for tests and building documentation. Packages `onnx` and `sphinx` which version are specified under the `tests/requirements.txt` file are required
-* a modern LaTeX compiler such as `lualatex` to compile the documentation
+  `.ocamlformat` file at the root of the directory;
+* a `python3` interpreter version 3.9 of higher is required for tests and building documentation. Packages `onnx` and `sphinx` which version are specified under the `tests/requirements.txt` file are required;
+* a modern LaTeX compiler such as `lualatex` to compile the documentation;
 * the `ocaml language server <https://github.com/ocaml/ocaml-lsp>`_ is optional
   but will vastly improve your development experience with OCaml.