doc/pgp-userid-remove.page: Fix string
"Personal PGP key" is not a list, and two very similar string has "from the list" (at C/pgp-userid-primary.page, line 35; C/subkeys-add.page, line 34) -- added "from the" to equalize to other string.
"Personal PGP key" is not a list, and two very similar string has "from the list" (at C/pgp-userid-primary.page, line 35; C/subkeys-add.page, line 34) -- added "from the" to equalize to other string.