Add "Running on Kestrel" section

[yandthj]

Like Swift and Vermilion, we need to add a section for information specific to running jobs on Kestrel, including partitions.

[yandthj]

PR #534 to add partitions table.

To do:

• [x] Add shared node partition information
• [x] link to general slurm section
• [ ] add job priorities section
• [ ] include info about qos (standby and high specifications)