Made repo root available for templates

This allows for embedding the repo root inside of, for example, scripts
to make them function properly no matter where they are run from.

templates/generate_configs.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 set -euo pipefail
-ROOT=$(git rev-parse --show-toplevel)
+ROOT={{ root }}
 CONFIGS=${ROOT}/configs
 
 # Generate the configuration for each node

tools/render

@@ -152,7 +152,9 @@ def main():
     for template_name in TEMPLATES.list_templates():
         template = TEMPLATES.get_template(template_name)
 
-        rendered = template.render(nodes=nodes, clusters=clusters, config=config)
+        rendered = template.render(
+            nodes=nodes, clusters=clusters, config=config, root=ROOT
+        )
         with open(RENDERED.joinpath(template_name), "w") as f:
             f.write(rendered)