Add tier badging to Charts install pages

What does this MR do?

This MR exclusively adds the **(FREE SELF)** tier badge to the top-level Charts index page, and to all of the doc pages in the /installation directory. Now that we're integrating this information more tightly with the rest of our documentation (via the combined global nav), it's helpful to readers to better surface the tiers that can access the described functionality in a doc page.

Author's checklist

• Follow the Documentation Guidelines and Style Guide.
• Ensure that the product tier badge is added to doc's h1.
• Request a review based on the documentation page's metadata and associated Technical Writer.

To avoid having this MR be added to code verification QA issues, don't add these labels: ~"feature", frontend, backend, ~"bug", or database

Review checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • If relevant to this MR, ensure content topic type principles are in use, including:
    • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
    • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
    • Any task steps should be written as a numbered list.
• Review by assigned maintainer, who can always request/require the above reviews. Maintainer's review can occur before or after a technical writer review.
• Ensure a release milestone is set.