Make "OCSP Responder" table headers sticky

[RufusJWB]

It would be nice, if the table header of the OCSP Responder overview table would be sticky while scrolling through the list. I think you could edit

certwatch_db/ocsp_responders/ocsp_responders.fnc

Line 379 in 572ab7d

<TH rowspan="2">Root Owner(s)</TH>

and add something like https://adrianroselli.com/2020/01/fixed-table-headers.html#Update02