Use the figure directive

Author: seisman

pygmt/params/pattern.py

@@ -26,9 +26,10 @@ class Pattern(BaseParam):
     GMT provides 90 predefined patterns that can be used in PyGMT. The patterns are
     numbered from 1 to 90, and shown below:
 
-    .. image:: https://docs.generic-mapping-tools.org/6.5/_images/GMT_App_E.png
+    .. figure:: https://docs.generic-mapping-tools.org/6.5/_images/GMT_App_E.png
        :alt: The 90 predefined bit-patterns provided with GMT
        :width: 75%
+       :align: center
 
     Parameters
     ----------