Add the ability to show instance descriptions

[MiguelAFH]

In many of the MedHELM scenarios, the data is redacted for compliance reasons. This makes the benchmark understanding difficult for users exploring the leaderboard.

The request is to add, possibly in the header of the benchmark page (see below), an example of what the model is being asked.

As an example, this is what we are including in the appendix of the paper to exemplify the task being evaluated.

[yifanmai]

#3755 provides the ability to provide both a short and a long description in the scenario run group description. You can put the instance examples in the long scenario descriptions by modifying schema_medhelm.yaml.

For instance, you would change this:

  - name: shc_ptbm_med
    display_name: ADHD-Behavior
    description: ADHD-Behavior is a benchmark that evaluates a model's ability to detect whether a clinician recommends parent training in behavior management, an evidence-based first-line treatment for young children diagnosed with ADHD. Each instance includes a clinical note from a pediatric visit and a binary classification task [(Pillai et al., 2024)](https://doi.org/10.1093/jamia/ocae001).

by renaming description to short_description and then adding your example in description:

  - name: shc_ptbm_med
    display_name: ADHD-Behavior
    short_description: ADHD-Behavior is a benchmark that evaluates a model's ability to detect whether a clinician recommends parent training in behavior management, an evidence-based first-line treatment for young children diagnosed with ADHD. Each instance includes a clinical note from a pediatric visit and a binary classification task [(Pillai et al., 2024)](https://doi.org/10.1093/jamia/ocae001).
    description: "ADHD-Behavior is a benchmark that evaluates a model's ability to detect whether a clinician recommends parent training in behavior management, an evidence-based first-line treatment for young children diagnosed with ADHD. Each instance includes a clinical note from a pediatric visit and a binary classification task [(Pillai et al., 2024)](https://doi.org/10.1093/jamia/ocae001).\n
      \n
      **Context**: The context includes a clinical note documenting...\n
      \n
      **Example**:\n
      \n
      ```\n
      Date: ...\n
      Patient: ...\n
      Visit Type: ...\n
      ```"

You will need to reformat your text from LaTeX to Markdown in YAML. It might be helpful to write a script to do this. You might also find this YAML multi-line string guide helpful.

After you've made the change, I will need to rebuild the live frontend to pick up these changes.