Doc: update README.md

README.md

@@ -8,3 +8,20 @@ Example `.pkg` file:
       url=git@github.com:motis-project/fmt.git
       branch=master
       commit=3eca62d66c7c9a2ca97dc8381299d911978b9fb2
+
+## Useful commands
+After invoking `CMake`, the `pkg` binary executable can be found in `build/dl/`.
+
+### Displaying the dependency tree
+
+    pkg -s
+
+### Syncing deps/
+After updating a commit ID in the `.pkg` file,
+you can `pkg -l` to establish the dependency tree state described in the `.pkg` file.
+Effectively, `git` repositories will be updated in `deps/`.
+
+You can use `-f` to force checkout the commits.
+
+> [!WARNING]
+> This will override the changes you made, so be careful.