docs: Created utils toctree

Author: daquinteroflex

docs/api/index.rst

@@ -23,6 +23,7 @@ API |:computer:|
     output_data
     scene
     logging
+    utilities
     submit_simulations
     mesh/index
     heat/index
@@ -37,6 +38,7 @@ API |:computer:|
     viz
 
 .. include:: /api/simulation.rst
+.. include:: /api/utilities.rst
 .. include:: /api/boundary_conditions.rst
 .. include:: /api/geometry.rst
 .. include:: /api/mediums.rst
@@ -62,4 +64,4 @@ API |:computer:|
 .. include:: /api/constants.rst
 .. include:: /api/abstract_base.rst
 .. include:: /api/abstract_models.rst
-.. include:: /api/viz.rst
+.. include:: /api/viz.rst

docs/api/simulation.rst

@@ -8,5 +8,3 @@ Simulation
    :template: module.rst
 
    tidy3d.Simulation
-   tidy3d.RunTimeSpec
-   tidy3d.FreqRange

docs/api/utils.rst

@@ -0,0 +1,12 @@
+.. currentmodule:: tidy3d
+
+Utilities
+=========
+
+.. autosummary::
+   :toctree: _autosummary/
+   :template: module.rst
+
+   tidy3d.RunTimeSpec
+   tidy3d.FreqRange
+   tidy3d.FreqUtils