Fix org settings navigation: 'Repository defaults' is now 'General' - #46026

Why:

Closes #46024

The organization settings sidebar no longer has a Repository defaults entry. The settings this step leads to now live under Repository → General.

What's being changed (if available, include any code snippets, screenshots, or gifs):

One-line text change in the reusable data/reusables/organizations/repository-defaults.md: "click Repository defaults" → "click General". The filename is unchanged, so every article that includes this reusable picks up the fix.

BEFORE:

AFTER:

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require an SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.