Fixes typo in the docs for adding your own library (#2520)

# Description

Fix the small stylistic mistake in the documentation. 

## Type of change

- Bug fix (non-breaking change which fixes an issue) (docs fix)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Signed-off-by: Norbert Cygiert <107721774+norbertcygiert@users.noreply.github.com>
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

CONTRIBUTORS.md

@@ -87,6 +87,7 @@ Guidelines for modifications:
 * Miguel Alonso Jr
 * Muhong Guo
 * Nicola Loi
+* Norbert Cygiert
 * Nuoyan Chen (Alvin)
 * Nuralem Abizov
 * Ori Gadot

docs/source/how-to/add_own_library.rst

@@ -63,7 +63,7 @@ Integrating a new library
 
 Adding a new library to Isaac Lab is similar to using a different version of a library. You can install the library
 in your Python environment and use it in your experiments. However, if you want to integrate the library with
-Isaac Lab, you can will first need to make a wrapper for the library, as explained in
+Isaac Lab, you will first need to make a wrapper for the library, as explained in
 :ref:`how-to-env-wrappers`.
 
 The following steps can be followed to integrate a new library with Isaac Lab: