Fix issues in Markdown doc files

[wenzeslaus]

Essential:

• implement fixes to remove ignores in linting config
• update r.landscape.evol Markdown to new doc
• remove block quotes from r.green tools
• check for image-alt text
• inspect images (by sampling, regexp)
• reduce cases where sh code blocks are used for things which are not sh
• put back meta page name and description info

Transition-related:

• put back meta page as YAML headers and level 1 headings

Optional:

• make Markdown tooling understand that some code blocks in r.fuzzy.system doc are its own specific syntax (and not an unnecessary $ sign in a Bash example).