doc: hacking: Quote perl5lib

Dependencies

• [2] DWMH6NFB docs: mention foreman under hacking
• [3] L4JYZ7BM doc: switch shell session code blocks to `console` type.
• [4] 3JXCTKEC Add markdown files for documentation

Change contents

• replacement in doc/manual/src/hacking.md at line 11
  [3.6989]→[2.11:82](∅→∅)
  − To enter a shell in which all environment variables (such as PERL5LIB)
  [3.6989]

  [2.82]
  + To enter a shell in which all environment variables (such as `PERL5LIB`)