Fix error message quotations in install_kdc.rst

Some error messages that kprop could print were quoted incorrectly in
install_kdc.rst.

Also fix minor typos.

(cherry picked from commit 68d7fcf11553c29a2e0c28a57896fbce4a3ef611)

https://github.com/krb5/krb5/commit/098ddc694ebb1356ec963a669339cd3c5a7fe44f
Author: Tom Yu <tlyu@mit.edu>
Commit: 098ddc694ebb1356ec963a669339cd3c5a7fe44f
Branch: krb5-1.11
 doc/admin/install_kdc.rst |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)