Update version and date for 4.18.

wiki/src/inc/stable_amd64_date.html

-2021-03-23
\ No newline at end of file
+2021-04-20
\ No newline at end of file

wiki/src/inc/stable_amd64_img_gpg_verify.html

-TZ=UTC gpg --no-options --keyid-format long --verify tails-amd64-4.17.img.sig tails-amd64-4.17.img
+TZ=UTC gpg --no-options --keyid-format long --verify tails-amd64-4.18.img.sig tails-amd64-4.18.img

wiki/src/inc/stable_amd64_img_sig_url.html

-https://tails.boum.org/torrents/files/tails-amd64-4.17.img.sig
+https://tails.boum.org/torrents/files/tails-amd64-4.18.img.sig

wiki/src/inc/stable_amd64_img_torrent_url.html

-https://tails.boum.org/torrents/files/tails-amd64-4.17.img.torrent
+https://tails.boum.org/torrents/files/tails-amd64-4.18.img.torrent

wiki/src/inc/stable_amd64_img_url.html

-http://dl.amnesia.boum.org/tails/stable/tails-amd64-4.17/tails-amd64-4.17.img
+http://dl.amnesia.boum.org/tails/stable/tails-amd64-4.18/tails-amd64-4.18.img

wiki/src/inc/stable_amd64_iso_gpg_verify.html

-TZ=UTC gpg --no-options --keyid-format long --verify tails-amd64-4.17.iso.sig tails-amd64-4.17.iso
+TZ=UTC gpg --no-options --keyid-format long --verify tails-amd64-4.18.iso.sig tails-amd64-4.18.iso

wiki/src/inc/stable_amd64_iso_sig_url.html

-https://tails.boum.org/torrents/files/tails-amd64-4.17.iso.sig
+https://tails.boum.org/torrents/files/tails-amd64-4.18.iso.sig

wiki/src/inc/stable_amd64_iso_torrent_url.html

-https://tails.boum.org/torrents/files/tails-amd64-4.17.iso.torrent
+https://tails.boum.org/torrents/files/tails-amd64-4.18.iso.torrent

wiki/src/inc/stable_amd64_iso_url.html

-http://dl.amnesia.boum.org/tails/stable/tails-amd64-4.17/tails-amd64-4.17.iso
+http://dl.amnesia.boum.org/tails/stable/tails-amd64-4.18/tails-amd64-4.18.iso

wiki/src/inc/stable_amd64_version.html

-4.17
+4.18