copy CNAME file using html_extra_path conf parameter

source/CNAME

@@ -0,0 +1 @@
+docs.opendronemap.org

source/conf.py

@@ -62,7 +62,7 @@ language = 'en'
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
 # This pattern also affects html_static_path and html_extra_path .
-exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store', 'arguments_edit']
 
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = 'sphinx'
@@ -99,6 +99,8 @@ html_theme_options = {
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
+html_extra_path = ['CNAME']
+
 # Custom sidebar templates, must be a dictionary that maps document names
 # to template names.
 #