DOC: Stop rendering plot directive figures to PDF (#884)

Co-authored-by: Melissa Weber Mendonça <melissawm@gmail.com>
Co-authored-by: Aditi Juneja <91629733+schefflera-arboricola@users.noreply.github.com>

Author: 3 people

doc/source/conf.py

@@ -367,7 +367,7 @@ def setup(app):
 
 # plot_directive options
 plot_include_source = True
-plot_formats = [('png', 96), 'pdf']
+plot_formats = [('png', 96)]
 plot_html_show_formats = False
 plot_html_show_source_link = False