Add ACM DL link for publications with no DOI

[khatchad]

If the DOI is not present but an acmid is, then please add a link to the ACM DL page. Currently, no link is generated.

[claudemarche]

the option
-f acmid
or
-nf acmid "ACM DL"
should do what you want

[khatchad]

Not quite. I get a link, but it's to a local file that doesn't exist. The link looks to be to a file in the working directory with the name of the ACM ID, e.g., file:///home/rk1424/Documents/Curriculum%20Vitae/2892681.