Fix typo in README description etc

[eMPee584]

• First, thanks for the useful tool 👍
• "An app" => tradition makes the indefinite english article 'a' turn to 'an' before a vowel sound:
  https://en.wikipedia.org/wiki/English_articles#Distinction_between_a_and_an
• Also, something is wrong with the module_update_at string in search results if a module is in multiple repositories it shows the oldest date for all versions.. it is correct in the individual module view.
• module versions from other repos can not be clicked, no link
• module webui X pages are not shown from mmrl but work from sukisu app 🤔