[html-formfu] Use uri_for in the form

[kewei xiao]

Hi Carl

    I am trying to put a link on my form to link to other page, I know I 
can use __uri_for(URI)__ in the yml file, but I am not exactly sure 
where I should put it.

   e.g,  I have link called "Lostpassword" on my form, when people click 
it, it will direct them to lostpassword page,

           here is what I am trying to do:
  
          - type: block
            tag: p
            content: Lostpassword
 
           then I am not sure where i can put my url

Ke Wei