Add docstring about force on elfeed-search-update.
Add docstring about force on elfeed-search-update.

algernon/elfeed,seblemaguer/elfeed,skeeto/elfeed,algernon/elfeed,seblemaguer/elfeed,holomorph/elfeed,holomorph/elfeed,daimrod/elfeed,daimrod/elfeed,jinnovation/elfeed,skeeto/elfeed,jinnovation/elfeed,emacsmirror/elfeed,emacsmirror/elfeed