PR idea for attributes

[jidanni]

I was going to make this PR to the manual:

               {#identifier .class1 .class2 key1=value1 key2=value2}                                 
                                                                                                     
       Thus, for example, the following headings can all be assigned attributes:                     
                                                                                                     
              # My heading {#foo1 .class1 .class2 key1=value1 key2=value2}                           
                                                                                                     
              ## My heading ## {#foo2 .class1 .class2 key1=value1 key2=value2}                       
                                                                                                     
              My other heading {#foo3 .class1 .class2 key1=value1 key2=value2}                       
              ---------------                                                                        

What does everybody think?