update doc configuration

doc/conf.py

@@ -34,15 +34,16 @@
     'sphinx.ext.todo',
     'sphinx.ext.mathjax',
     'sphinx.ext.viewcode',
-    'sphinx.ext.napoleon'
+    'sphinx.ext.napoleon',
+    'sphinx_rtd_theme',
 ]
 
 # Configuration for intersphinx, copied from astropy.
 intersphinx_mapping = {
     'python': ('https://docs.python.org/3/', None),
     'numpy': ('https://numpy.org/doc/stable/', None),
-    'scipy': ('https://docs.scipy.org/doc/scipy/reference/', None),
-    'matplotlib': ('https://matplotlib.org/', None),
+    'scipy': ('https://docs.scipy.org/doc/scipy/', None),
+    'matplotlib': ('https://matplotlib.org/stable/', None),
     'astropy': ('https://docs.astropy.org/en/stable/', None),
     'h5py': ('https://docs.h5py.org/en/latest/', None)
     }
@@ -132,12 +133,7 @@
 # a list of builtin themes.
 #html_theme = 'default'
 #html_theme = 'haiku'
-try:
-    import sphinx_rtd_theme
-    html_theme = 'sphinx_rtd_theme'
-    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-except ImportError:
-    pass
+html_theme = 'sphinx_rtd_theme'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the