docs: Add singleton tables documentation

conftest.py

@@ -0,0 +1,35 @@
+"""
+Pytest configuration for notebook tests.
+
+Configures DataJoint from environment variables before any tests run.
+This separates configuration from workflow execution.
+
+Usage:
+    # MySQL (default)
+    DJ_HOST=localhost DJ_USER=root DJ_PASS=tutorial pytest --nbmake ...
+
+    # PostgreSQL
+    DJ_HOST=localhost DJ_PORT=5432 DJ_USER=datajoint DJ_PASS=tutorial DJ_BACKEND=postgresql pytest --nbmake ...
+"""
+
+import os
+
+
+def pytest_configure(config):
+    """Configure DataJoint from environment variables before tests run."""
+    import datajoint as dj
+
+    # Database connection settings
+    if os.getenv('DJ_HOST'):
+        dj.config['database.host'] = os.getenv('DJ_HOST')
+    if os.getenv('DJ_PORT'):
+        dj.config['database.port'] = int(os.getenv('DJ_PORT'))
+    if os.getenv('DJ_USER'):
+        dj.config['database.user'] = os.getenv('DJ_USER')
+    if os.getenv('DJ_PASS'):
+        dj.config['database.password'] = os.getenv('DJ_PASS')
+    if os.getenv('DJ_BACKEND'):
+        dj.config['database.backend'] = os.getenv('DJ_BACKEND')
+
+    # Display settings for notebooks
+    dj.config['display.limit'] = 8