docs: user/getting_started: add dependencies

Changing the docs as well was missed in b1cdcc87

Reported-in: https://github.com/freifunk-gluon/gluon/pull/3414
Reported-by: @ChristianMiddendorf
Co-authored-by: @ChristianMiddendorf

docs/user/getting_started.rst

@@ -29,8 +29,10 @@ freshly installed Debian Bullseye system the following packages are required:
 
 * `git` (to get Gluon and other dependencies)
 * `python3`
+* `python3-dev`
+* `python3-pyelftools`
+* `python3-setuptools`
 * `build-essential`
-* `ecdsautils` (to sign firmware, see `contrib/sign.sh`)
 * `gawk`
 * `unzip`
 * `libncurses-dev` (actually `libncurses5-dev`)
@@ -41,6 +43,8 @@ freshly installed Debian Bullseye system the following packages are required:
 * `rsync`
 * `time` (built-in `time` doesn't work)
 * `qemu-utils`
+* `ecdsautils` (to sign firmware, see `contrib/sign.sh`)
+* `swig`
 
 We also provide a container environment that already tracks all these dependencies. It quickly gets you up and running, if you already have either Docker or Podman installed locally.