Fix README and docbook because of other manpage section

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Fix typos

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Remove references to parameter -C
because it's not implemented in plctool

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Merge pull request #6 from I2SE/master

Few documentation fixes