Sync EXTENDING docs re: system fonts

docs/sv_SE.UTF-8/EXTENDING.txt

@@ -5,7 +5,7 @@
          Copyright © 2002-2025 av olika bidragsgivare; se AUTHORS.txt.
                              https://tuxpaint.org/
 
-                                  maj 2, 2025
+                                 juni 8, 2025
 
 +------------------------------------------+
 |                 Innehåll                 |
@@ -24,6 +24,8 @@
 |       + Alternativ för stämplar          |
 |       + Förspeglade och omvända stämplar |
 |   * Typsnitt                             |
+|       + System Fonts                     |
+|       + FontConfig                       |
 |   * "Startbilder"                        |
 |       + Startbok i målarboksstil         |
 |       + Startbilder i scenformat         |
@@ -592,6 +594,52 @@ och "Etikett" kommer Rita med Tux att presentera teckensnittet i
 "Letters"-väljaren till höger, tillsammans med alternativ för att aktivera fet
 och/eller kursiv stil och ändra storleken.
 
+                             ### System Fonts ###
+
+Tux Paint checks a number of standard Operating System locations for fonts that
+the 'Text' and 'Label' tools might be able to use (unless the "--nosysfonts"
+option is set). The locations vary, depending on operating system.
+
+  * Windows
+      + The location specified by the "Fonts" option of the "Software\Microsoft
+        \Windows\CurrentVersion\Explorer\Shell Folders" Windows Registry key.
+      + If the above fails, then "C:\WINDOWS\FONTS".
+      + The location specified by the "Local AppData" option of the "Software\
+        Microsoft\Windows\CurrentVersion\Explorer\Shell Folders" Windows
+        Registry key. The path "\Microsoft\Windows\Fonts" is appended to that
+        location.
+  * macOS
+      + /System/Library/Fonts
+      + /Library/Fonts
+      + /usr/share/fonts
+      + /usr/X11R6/lib/X11/fonts
+      + The "Library/Fonts" folder in the user's home folder.
+  * Android
+      + /system/fonts
+  * Haiku
+
+    The locations found by asking Haiku's "Storage Kit" to find the directories
+    on the "/boot" volume for:
+      + B_SYSTEM_FONTS_DIRECTORY
+      + B_SYSTEM_NONPACKAGED_FONTS_DIRECTORY
+      + B_USER_FONTS_DIRECTORY
+      + B_USER_NONPACKAGED_FONTS_DIRECTORY
+
+  * Linux
+      + /usr/share/feh/fonts
+      + /usr/share/fonts
+      + /usr/X11R6/lib/X11/fonts
+      + /usr/share/texmf/fonts
+      + /usr/share/grace/fonts/type1
+      + /usr/share/hatman/fonts
+      + /usr/share/icewm/themes/jim-mac
+      + /usr/share/vlc/skins2/fonts
+      + /usr/share/xplanet/fonts
+
+                              ### FontConfig ###
+
+...
+
 "Startbilder"
 
 "Startbilder" visas i dialogrutan "Ny", tillsammans med val av bakgrund i