Add invoice for @wooorm

Closes GH-59.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Remco Haszing <remcohaszing@gmail.com>

invoices/2023-01-31-wooorm.md

@@ -0,0 +1,24 @@
+# Invoice: unified collective
+
+*   **Date**: 2023-01-31
+*   **Person**: Titus Wormer ([**@wooorm**](https://github.com/wooorm))
+
+## Items
+
+| Item               | Description                       | Total         |
+| ------------------ | --------------------------------- | ------------- |
+| unified collective | Development and support (January) | **$4,800.00** |
+
+***
+
+The numbers for this month:
+
+*   **Commits**: [1311](https://github.com/search?q=author%3Awooorm+committer-date%3A%222022-12-31..2023-01-31%22)
+*   **Issues and PRs**: [4](https://github.com/search?q=author%3Awooorm+created%3A%222022-12-31..2023-01-31%22)
+*   **Reviews**: [46](https://github.com/search?q=reviewed-by%3Awooorm+created%3A%222022-12-31..2023-01-31%22)
+
+The numbers since the previous invoice, on 2022-04-30.
+
+*   **Commits**: [3957](https://github.com/search?q=author%3Awooorm+committer-date%3A%222022-04-30..2023-01-31%22)
+*   **Issues and PRs**: [64](https://github.com/search?q=author%3Awooorm+created%3A%222022-04-30..2023-01-31%22)
+*   **Reviews**: [247](https://github.com/search?q=reviewed-by%3Awooorm+created%3A%222022-04-30..2023-01-31%22)