A civil action cannot be maintained against any person, firm or corporation, for the publication of a fair and true report of any judicial proceeding, legislative proceeding or other official proceeding, or for any heading of the report which is a fair and true headnote of the statement published. This section does not apply to a libel contained in any other matter added by any person concerned in the publication; or in the report of anything said or done at the time and place of such a proceeding