Fix broken links / minor wording changes

[sspencerwire]

• Removed "ghostwriter" as the project goes to a GitHub account with a 404 error. In a search, could not find "ghostwriter" available at all, except in some forks for KDE. Believe this project is dead.
• Replaced expired domain for "Mark Text" with the current GitHub link.
• "Remarkable" is now has a Windows version, so this has been added to the description.
• minor wording change in section dealing with documentation subjects

Author checklist (Completed by original Author)

• Contribution a good fit for the Rocky project? Title and Author MetaTags inserted ?
• Is this a non-English contribution?
• 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 (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)
• Final pass/approval (Final Review)