Update infos about AUR package

Dependencies

• [2] JHJB5ZQX Removing conflict markers
• [3] LLS53CR2 Add installation instructions for openSUSE Tumbleweed
• [4] SCSV2FNS Reboot
• [5] BRV6TU4B Turning the Installation page more beginner-friendly

Change contents

• resolve order conflict in src/installing.md at line 44
  [3.138]

  [3.1365]
• replacement in src/installing.md at line 98
  [2.1]→[3.1621:1771](∅→∅),[3.308810]→[3.1621:1771](∅→∅)
  − Pijul is packaged in [AUR](https://aur.archlinux.org/packages/pijul/); however, this package is currently flagged Out-of-date and seems to be broken.
  [2.1]

  [3.308895]
  + Pijul is packaged in [AUR](https://aur.archlinux.org/packages/pijul/). It should be up-to-date or at least close.