1) Better fix for section "Readline Killing Commands": delete entire

1) Better fix for section "Readline Killing Commands": delete entire
first paragraph.  It looks like it's left over from previous
nomenclature; term "cutting" introduced there is not used in rest of
document.  ("killing" is used instead, as in the section title and in
the following paragraph.)

2) More consistent use of @key for things to type in; in a few cases
not having it actually produced wrong doc on paper---notably "M--"
comes out as "M" followed by emdash, if in the plain Roman body
text...