Update history (#653)

Co-authored-by: Sonny Piers <sonny@fastmail.net>

source/about.html.haml

@@ -85,6 +85,9 @@ description: About Flatpak
           .date June 2016
           .description
             Work on desktop portals security framework begins
+          .date June 2016
+          .description
+            LibreOffice is the first major application to adopt Flatpak for publishing on Linux
           .date July 2016
           .description
             GTK+ 3.21.4 released with initial support for the portals framework
@@ -109,12 +112,54 @@ description: About Flatpak
           .date October 2017
           .description
             KDE Plasma 5.11 released, “Discover” gains the ability to install Flatpak apps
+          .date October 2017
+          .description
+            GIMP adopts Flatpak to publish on Linux
           .date November 2017
           .description
             Linux Mint 18.3 released, includes out of the box Flatpak integration
           .date August 2018
           .description
             Flatpak 1.0 released, the first release in a new stable series, with major new features; Flathub beta period ends; Freedesktop runtime 18.08 released with new support period policy
+          .date September 2018
+          .description
+            KDE introduces the KDE Testing Applications Flatpak repository;
+            =link_to "commit", "https://invent.kde.org/packaging/flatpak-kde-applications/-/commit/2d759a0d601942c3cf3a1d6a562942da543f7f83"
           .date December 2019
           .description
             elementary OS 5.1 Hera released, includes out of the box Flatpak integration
+          .date April 2020
+          .description
+            Mozilla adopts Flatpak to publish Firefox on Linux
+          .date April 2020
+          .description
+            System76 releases Pop!_OS 20.04, includes out of the box Flatpak integration
+          .date October 2021
+          .description
+            1Password adopts Flatpak to publish on Linux
+          .date Febuary 2022
+          .description
+            Valve releases the Steam Deck; a handheld video game console with out of the box Flatpak and Flathub integration
+          .date Febuary 2022
+          .description
+            OBS Studio adopts Flatpak to publish on Linux
+          .date May 2022
+          .description
+            Red Hat Enterprise Linux Workstation 9 released, includes out of the box Flatpak integration
+          .date October 2022
+          .description
+            Flathub introduces verified status;
+            =link_to "commit", "https://github.com/flathub/website/commit/5aae6b759b15ae26c155a0c8c18f13ca0da29ee3"
+          .date April 2023
+          .description
+            Purism introduces Flatpak and the PureOS Flatpak repository;
+            =link_to "announcement", "https://puri.sm/posts/introducing-flatpaks-on-pureos/"
+          .date April 2023
+          .description
+            Valve adopts portals for the popular Steam application
+          .date May 2023
+          .description
+            Flathub offers more than 2000 apps and celebrates 1B total downloads
+          .date October 2023
+          .description
+            Discord adopts Flatpak to publish on Linux