Rewrite cron procedure to include references to anacron

[sspencerwire]

• Fix incorrect headers (more than one top level "#")
• Fix missing word issue
• Describe in brief the relationship between cron and anacron
• Provide links to the anacron procedure for more information on that
• Modified the "dot" file definitions and added a note to indicate
  anacron's relationship to these files
• Lab tested the @options to make sure that they still operate like they
  used to (not randomized by anacron) proven with a lab test of the
  @daily option
• Added a few admonitions (!!! note) to emphasize a few issues
• set cron, crontab and anacron references in code block as all
  three are commands
• added updated meta and date in the meta section at the top

Author checklist (to be completed by original Author)

• Is this document a good fit for the Rocky project ?
• Is this a non-English contribution?
• Title and Author MetaTags have been inserted into the document
• If applicable, steps and instructions have been tested to work on a real system
• Did you perform an initial self-review to fix basic typos and grammatical correctness

Rocky Documentation checklist (to be completed by Rocky team)

• 1st Pass (Check that document is good fit for project and author checklist completed)
• 2nd Pass (Technical Review - check for technical correctness)
• 3rd Pass (Basic Editorial Review)
• 4th Pass (Detailed Editorial Review and Peer Review)
• 5th Pass (Include document in TOC)
• Final pass/approval (Final Review)