Add git source docs, weekly FreeCAD, update_check URLs

- FreeCAD updated to weekly-2026.03.19 development builds
  Source: github.com/FreeCAD/FreeCAD/releases (weekly tags)
- dwl package: added update_check URL and git source comments
- README: added standalone repo notice and submodule reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/dwl/dwl.toml

@@ -6,15 +6,28 @@ url = "https://codeberg.org/dwl/dwl"
 license = "GPL-3.0"
 
 [source]
+# Tarball release (default)
 url = "https://codeberg.org/dwl/dwl/archive/v${version}.tar.gz"
 sha256 = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
 
+# To build from git main branch instead, change to:
+#   url = ""
+#   sha256 = "SKIP"
+#   git = "https://codeberg.org/dwl/dwl.git"
+#   branch = "main"
+#
+# To pin to a specific tag:
+#   git = "https://codeberg.org/dwl/dwl.git"
+#   tag = "v${version}"
+
+update_check = "https://codeberg.org/api/v1/repos/dwl/dwl/releases/latest"
+
 [dependencies]
 run = ["wlroots", "wayland", "wayland-protocols", "libinput", "xwayland"]
 build = ["gcc", "make", "pkg-config"]
 
 [build]
 system = "custom"
-configure = """"""
-make = """make"""
-install = """make DESTDIR=${PKG} PREFIX=/usr install"""
+configure = ""
+make = "make"
+install = "make DESTDIR=${PKG} PREFIX=/usr install"