Fix bugs, adjust README

[pitrson]

Addresses #2

README.md

• adjusted to add examples on how to:
  • set unlimited amount of generated pages (new)
  • how to use '+tag' (code was there, but not mentioned in README

Pagelist

• fixed bug in regex in re.finditer
  • fixes unwated behavior where e.g. {pagelist index1} would be matched as {pagelist i} - tags starting with either 'g' or 'i' would trigger this bug (tested via https://pythex.org/ )
• if pagelist is called with first argument being 0 it would treat the limit as None. This is a workaround, because of the way the pagelist logic is written in - it always expects either 'i', 'g' or digit as a first arguments and behaves wrongly if it's not there. Workarounds scenarios where e.g. instead of {pagelist tag1} - not working , user should configure {pagelist 0 tag1} instead
• adjusted logic for link generation to omit generating the link for the same page the plugin is supposed to generate links on as I don't see any use-case for this

[alanpt]

Looks good to me.