Update README.

README.md

@@ -30,3 +30,28 @@ of packages to your needs:
 | `mo2-dds-header` | Small port to bring the DirectXTex `DDS.h` header. |
 | `mo2-libbsarch` | Port for [libbsarch](https://github.com/ModOrganizer2/libbarch), using the prebuilt release available. |
 | `spdlog` | For of the official `spdlog` port to remove `fmt` dependency and force the use of `std::format` instead. |
+
+## Updating a dependency
+
+1. Manually modify `vcpkg.json` and `portfile.cmake` for the dependency you want to update
+under ports:
+    - Update the version (and other stuff if needed) in `vcpkg.json`.
+    - Update (at least) the HASH of the file in `portfile.cmake`.
+
+2. Make a commit with the change, see format of previous commit, e.g.,
+
+    [mo2-libloot] Bump to 0.26.2.
+
+3. Run the following:
+
+    ```powershell
+    vcpkg --x-builtin-ports-root=./ports `
+      --x-builtin-registry-versions-dir=./versions x-add-version `
+      --all --verbose --overwrite-version
+    ```
+
+4. Make a commit with all changes under `versions` with message
+
+    [registry] Update versions database.
+
+5. Push the change to the repository.