doc: Update URLs for Proclamation

CONTRIBUTING.md

···
   the build system automatically turns on quite a few of them.
   If you can't figure out a warning, mention it in the request so we can figure it out together.
 
-- We use [Proclamation](https://gitlab.com/ryanpavlik/proclamation) to generate release notes.
+- We use [Proclamation](https://gitlab.com/proclamation/proclamation) to generate release notes.
   After creating a merge request for a substantial change, please create one or more changelog
   fragments on the branch describing the changes.  See
   [doc/changes/README.md](doc/changes/README.md) for more info.

doc/changes/.proclamation.json

···
 {
-    "$schema": "https://ryanpavlik.gitlab.io/proclamation/proclamation.schema.json",
-    "#": "This is a config file for Proclamation, the changelog combiner: https://gitlab.com/ryanpavlik/proclamation",
+    "$schema": "https://proclamation.gitlab.io/proclamation/proclamation.schema.json",
+    "#": "This is a config file for Proclamation, the changelog combiner: https://gitlab.com/proclamation/proclamation",
     "SPDX-License-Identifier: CC0-1.0": "",
     "SPDX-FileCopyrightText: 2020 Collabora, Ltd. and the Proclamation contributors": "",
     "project_name": "Monado",

doc/changes/README.md

···
   - Config file: default name (`.proclamation.json`)
 - Location of the per-changelog-section directories: `doc/changes`
 
-[Proclamation]: https://gitlab.com/ryanpavlik/proclamation
+[Proclamation]: https://gitlab.com/proclamation/proclamation
 
 ## Table of Contents
 

doc/conventions.md

···
 [example1]: https://gitlab.freedesktop.org/monado/monado/-/commit/5e0f0866a6f74116acbc46c6e2447fdb8c716d02
 [example2]: https://gitlab.freedesktop.org/monado/monado/-/commit/98a5b18e0f90dab9f2ea5c2bbfd4ccd4998121c4
 [example3]: https://gitlab.freedesktop.org/monado/monado/-/commit/785e99f115df87dd4561fe6f88a7988b5834b650
-[proclamation]: https://gitlab.com/ryanpavlik/proclamation
+[proclamation]: https://gitlab.com/proclamation/proclamation
 
 ## APIs