Sync EXTENDING docs re: system fonts

docs/is_IS.UTF-8/EXTENDING.txt

@@ -5,7 +5,7 @@
         Copyright © 2002-2025 by various contributors; see AUTHORS.txt.
                              https://tuxpaint.org/
 
-                                  maí 2, 2025
+                                 júní 8, 2025
 
 +-----------------------------------------+
 |            Table of Contents            |
@@ -24,6 +24,8 @@
 |       + Stamp Options                   |
 |       + Pre-Mirrored and Flipped Stamps |
 |   * Fonts                               |
+|       + System Fonts                    |
+|       + FontConfig                      |
 |   * 'Starters'                          |
 |       + Coloring-Book Style Starters    |
 |       + Scene-Style Starters            |
@@ -587,6 +589,52 @@ Simply place them in the "fonts" directory. When using the 'Text' and 'Label'
 tools, Tux Paint will present the font in the 'Letters' selector at the right,
 along with options to enable bold and/or italics, and change the size.
 
+                             ### 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 ###
+
+...
+
 'Starters'
 
 'Starter' images appear in the 'New' dialog, along with solid color background