Update to doc of installing mujoco

potatolige: <p>Hi,</p>
<p>I found a cool guideline for installing mujoco from a PyTorch doc <a href="https://pytorch.org/rl/reference/generated/knowledge_base/MUJOCO_INSTALLATION.html" class="inline-onebox" rel="noopener nofollow ugc">Working with MuJoCo-based environments — torchrl main documentation</a>. But I suffered some different problems and found a solution, which was not listed in this doc.</p>
<p>I would like to add a troubleshooting paragraph to the doc, but I could not find the source of the doc. So I post it here.</p>
<p>The problem is that I need to install metaworld RL benchmark which depends on the old mujoco_py stuff. During the compiling, such as calling “import mujoco_py” after “pip install mujoco_py”, some errors will raise:<br>
cannot find -lGL: No such file or directory</p>
<p>My solution is to call “conda install -c anaconda mesa-libgl-devel-cos6-x86_64” which is different from the suggested package “mesa-libgl-cos6-x86_64” in the doc.</p>
<p>I hope my wasted time will help someone get out of this trap.</p>
<p>Best,<br>
Bruce</p>

ptrblck: <p>The source file can be found <a href="https://github.com/pytorch/rl/blob/0d0879c4a59b74b4816dfaf7670a32f7d45c83cf/knowledge_base/MUJOCO_INSTALLATION.md">here</a>.<br>
Would you mind creating an issue in their GitHub repository so that the code owners could take a look at your issue and update the docs if needed?</p>

vmoens: <p><a class="mention" href="/u/ptrblck">@ptrblck</a> you took the words right out of my mouth!<br>
The file is fetched and synced from a .md<br>
Glad that you find it useful! Those mujoco issues can be very annoying and it’s great if we can keep them in one place!</p>

vmoens: <p><a class="mention" href="/u/potatolige">@potatolige</a></p>
<p>see</p><aside class="onebox githubpullrequest" data-onebox-src="https://github.com/pytorch/rl/pull/1073">
  <header class="source">

      <a href="https://github.com/pytorch/rl/pull/1073" target="_blank" rel="noopener nofollow ugc">github.com/pytorch/rl</a>
  </header>

  <article class="onebox-body">
    <div class="github-row">



    <div class="github-icon-container" title="Pull Request">
      <svg width="60" height="60" class="github-icon" viewbox="0 0 12 16" aria-hidden="true"><path fill-rule="evenodd" d="M11 11.28V5c-.03-.78-.34-1.47-.94-2.06C9.46 2.35 8.78 2.03 8 2H7V0L4 3l3 3V4h1c.27.02.48.11.69.31.21.2.3.42.31.69v6.28A1.993 1.993 0 0 0 10 15a1.993 1.993 0 0 0 1-3.72zm-1 2.92c-.66 0-1.2-.55-1.2-1.2 0-.65.55-1.2 1.2-1.2.65 0 1.2.55 1.2 1.2 0 .65-.55 1.2-1.2 1.2zM4 3c0-1.11-.89-2-2-2a1.993 1.993 0 0 0-1 3.72v6.56A1.993 1.993 0 0 0 2 15a1.993 1.993 0 0 0 1-3.72V4.72c.59-.34 1-.98 1-1.72zm-.8 10c0 .66-.55 1.2-1.2 1.2-.65 0-1.2-.55-1.2-1.2 0-.65.55-1.2 1.2-1.2.65 0 1.2.55 1.2 1.2zM2 4.2C1.34 4.2.8 3.65.8 3c0-.65.55-1.2 1.2-1.2.65 0 1.2.55 1.2 1.2 0 .65-.55 1.2-1.2 1.2z"></path></svg>
    </div>

  <div class="github-info-container">



      <h4>
        <a href="https://github.com/pytorch/rl/pull/1073" target="_blank" rel="noopener nofollow ugc">[Doc] Update KB: cannot find -lGL</a>
      </h4>

    <div class="branches">
      <code>pytorch:main</code> ← <code>pytorch:update_kb</code>
    </div>

      <div class="github-info">
        <div class="date">
          opened <span class="discourse-local-date" data-format="ll" data-date="2023-04-19" data-time="12:03:49" data-timezone="UTC">12:03PM - 19 Apr 23 UTC</span>
        </div>

        <div class="user">
          <a href="https://github.com/vmoens" target="_blank" rel="noopener nofollow ugc">
            <img alt="vmoens" src="https://avatars.githubusercontent.com/u/25529882?v=4" class="onebox-avatar-inline" width="20" height="20">
            vmoens
          </a>
        </div>

        <div class="lines" title="1 commits changed 1 files with 4 additions and 0 deletions">
          <a href="https://github.com/pytorch/rl/pull/1073/files" target="_blank" rel="noopener nofollow ugc">
            <span class="added">+4</span>
            <span class="removed">-0</span>
          </a>
        </div>
      </div>
  </div>
</div>

  <div class="github-row">
    <p class="github-body-container">## Description

Describe your changes in detail.

## Motivation and Context

Why<span class="show-more-container"><a href="https://github.com/pytorch/rl/pull/1073" target="_blank" rel="noopener nofollow ugc" class="show-more">…</a></span><span class="excerpt hidden"> is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.
You can use the syntax `close #15213` if this solves the issue #15213

- [ ] I have raised an issue to propose this change ([required](https://github.com/pytorch/rl/issues) for new features and bug fixes)

## Types of changes

What types of changes does your code introduce? Remove all that do not apply:

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds core functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
- [ ] Documentation (update in the documentation)
- [ ] Example (update in the folder of examples)

## Checklist

Go over all the following points, and put an `x` in all the boxes that apply.
If you are unsure about any of these, don't hesitate to ask. We are here to help!

- [ ] I have read the [CONTRIBUTION](https://github.com/pytorch/rl/blob/main/CONTRIBUTING.md) guide (**required**)
- [ ] My change requires a change to the documentation.
- [ ] I have updated the tests accordingly (*required for a bug fix or a new feature*).
- [ ] I have updated the documentation accordingly.</span></p>
  </div>

  </article>

  <div class="onebox-metadata">
    
    
  </div>

  <div style="clear: both"></div>
</aside>