Update GNU Fortran documentation (6.3.0)

lib/docs/filters/gnu/clean_html.rb

@@ -26,7 +26,7 @@ module Docs
           node.inner_html = node.inner_html.strip_heredoc.strip
         end
 
-        css('dt > em', 'acronym', 'dfn', 'cite').each do |node|
+        css('dt > em', 'acronym', 'dfn', 'cite', 'h1 code').each do |node|
           node.before(node.children).remove
         end
 

lib/docs/scrapers/gnu/gnu_fortran.rb

@@ -7,7 +7,7 @@ module Docs
     }
 
     version '6' do
-      self.release = '6.1.0'
+      self.release = '6.3.0'
       self.dir = '/Users/Thibaut/DevDocs/Docs/gfortran6'
       self.base_url = "https://gcc.gnu.org/onlinedocs/gcc-#{release}/gfortran/"
     end