Fix Vale issues in Runner documentation

The GitLab Runner documentation has several issues identified by Vale. Additionally, some topics are too lengthy and need to be split into smaller, more manageable sections. They should be appropriately grouped in the left nav for better navigation.

I'm planning to read through the entire runner documentation to fix as much issues as I can. To achieve this, I'm planning to analyze page view data to prioritize which topics are most frequently accessed. This approach will help address the most viewed topics first.

Tasks

• Analyze page view data to identify the most frequently viewed topics and start working on that order
• Fix Vale issues
  • Review the Vale linting reports for style violations and fix any identified issues
  • Address consistency and tone issues
• Fix lengthy topics and update left nav
  • Identify topics that are too long and could be broken down into smaller sections.
  • Update left nav if required