Move 'set' lower in RECOMMENDED READING ORDER, just before 'getopts'
Move 'exit' lower in RECOMMENDED READING ORDER

I moved it just after section '2.8 Exit Status and Errors'.
Move 'cat' just after 'read' in RECOMMENDED READING ORDER
Move 'dot' lower in RECOMMENDED READING ORDER

I moved it just after the section '2.12 Shell Execution Environment'.