Write a service (or maybe information?) page about getting a WEIRS number

**What is the URL?**
Mentioned on the "[Get a central preparation facility](https://docs.google.com/document/d/1rOSfqLz7A_nx5Pt3tRfkH6jECCU5jSKXtLbQSJBG-F0/edit)" service page.

**Have you documented this via the author notes field in Joplin?**
- [x] Yes!
- [ ] No, but I'll do it now

**Describe the content debt.**

There's very little information on austintexas.gov about WEIRS numbers, what they are, and how to get them. For now, we're pointing to the help page, which has links to most of what users need to get started: https://www.austintexas.gov/water/weirs/cust/index.cfm?fuseaction=home.loginHelp

**What is the long-term, ideal solution for this content debt?**
- It kicks off the Austin Water content transition.
- We get a clear, actionable service page for any resident who needs a WEIRS number.

**Is this related to a feature request issue? (Add the issue number below and add the issue as a dependency.)**
Nope.

**What approvals will be needed to publish this content change?**

Austin Water

Start with the existing help page for WEIRS numbers and the linked “Get a central preparation facility” service page, then review the Joplin author notes for context. Done means a clear, actionable service or information page explaining what a WEIRS number is and how residents obtain one, with Austin Water approval before publication.

Written by the indexing model from the issue text.