Low: doc: fix typos in index terms

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
Med: fix xml.c memleak in "missing upgrade XSLT" case

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
Merge pull request #601 from jnpkrn/fix-xml.c-memleak

Fix xml.c memleak + doc: fix typos in index terms