docs: add environment modulefile instructions to README

README.md

@@ -70,6 +70,26 @@ cargo install --path .
 # Binary at bin/keep
 ```
 
+### Environment Module
+
+A TCL modulefile is provided at `modulefile`. To use it, copy or symlink the project directory into your modules path:
+
+```sh
+# Symlink into an existing module path (e.g., /usr/local/modules)
+ln -s /path/to/keep /usr/local/modules/keep
+
+# Load the module
+module load keep
+
+# Verify
+keep --status
+
+# Source the shell profile (optional, for shell integration)
+source $KEEP_BASH_PROFILE
+```
+
+The modulefile prepends `keep/bin` to `PATH` and sets `KEEP_BASH_PROFILE` pointing to `profile.bash`.
+
 ### Build with Server/Client Features
 
 ```sh