Fix all documentation build errors

- Fixed docstring indentation errors by using proper RST syntax (::)
- Fixed cost_tracking_decorator Example section formatting
- Fixed ClusterfyMagics.clusterfy Usage section formatting
- Added proper module-level documentation for DEFAULT_CONFIGS using #: syntax
- Fixed RST title underline lengths in config.rst
- Removed trailing spaces from "Cluster Settings" title

Documentation now builds without any errors or warnings.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

clustrix/cost_monitoring.py

@@ -257,7 +257,8 @@ def cost_tracking_decorator(provider: str, instance_type: str = "default"):
         provider: Cloud provider name (e.g., 'lambda', 'aws', 'azure', 'gcp')
         instance_type: Instance type for cost estimation
 
-    Example:
+    Example::
+
         @cost_tracking_decorator('lambda', 'a100_40gb')
         @cluster(cores=8, memory="32GB")
         def my_training_function():

clustrix/notebook_magic.py

@@ -185,7 +185,11 @@ class widgets:  # type: ignore
 from .config import configure, get_config
 
 logger = logging.getLogger(__name__)
-# Default cluster configurations
+
+#: Default cluster configurations available in the widget.
+#: 
+#: This dictionary contains pre-configured cluster templates for common use cases.
+#: Each configuration is a dictionary with cluster-specific settings.
 DEFAULT_CONFIGS = {
     "Local Single-core": {
         "cluster_type": "local",
@@ -2363,9 +2367,13 @@ class ClusterfyMagics(Magics):
     def clusterfy(self, line, cell):
         """
         Create an interactive widget for managing Clustrix configurations.
-        Usage:
+        
+        Usage::
+        
             %%clusterfy
+            
         This creates a widget interface that allows you to:
+        
         - Select and manage cluster configurations
         - Create new configurations with validation
         - Save/load configurations from files

docs/build/doctrees/api/config.doctree

@@ -9,10 +9,10 @@ Clustrix provides flexible configuration management for cluster settings, authen
    :show-inheritance:
 
 Configuration Methods
---------------------
+---------------------
 
 Programmatic Configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. code-block:: python
 
@@ -79,8 +79,8 @@ Authentication
 - ``password``: SSH password (not recommended)
 - ``key_file``: Path to SSH private key file
 
-Cluster Settings  
-~~~~~~~~~~~~~~~
+Cluster Settings
+~~~~~~~~~~~~~~~~
 
 - ``cluster_type``: Type of cluster (slurm, pbs, sge, kubernetes, ssh)
 - ``cluster_host``: Hostname of cluster head node