Add Git submodule for Renfe feeds and update configuration files

- Introduced a Git submodule for automatic downloading and patching of Renfe feeds.
- Updated README.md to include instructions for initializing submodules.
- Modified Taskfile.yml to streamline Renfe data downloading process.
- Adjusted build-config.json to reference new Santiago feed.
- Created otp-config.json to configure OTP features.

1 files changed, 0 insertions, 0 deletions

diff --git a/build_renfe b/build_renfe
new file mode 160000
+Subproject df68ee9059f21fe25e19b8ed65f7da387a92461