In this online help page: https://help.libreoffice.org/Writer/Adding_or_Deleting_a_Row_or_Column_to_a_Table_Using_the_Keyboard It is written that pressing Alt+Insert in a table cell and then an arrow key to insert a row or column. I'm using LO Writer 6.1.1 but Alt+Insert has no effect. Notice that the help page was last edited in 2011. Maybe its content is no more true?
This was changed with Bug 116452 - Remove "3 seconds to add/delete col/row" functions in version 6.1.0. The help site you mentioned is outdated. The current help site is available at https://help.libreoffice.org/ The right help page is already corrected: https://help.libreoffice.org/6.1/en-US/text/swriter/04/01020000.html?&DbPAR=WRITER&System=WIN Compare with the old version: https://help.libreoffice.org/6.0/en-US/text/swriter/04/01020000.html?&DbPAR=WRITER&System=WIN I set this bug as RESOLVED WORKSFORME.