Update the Silesian flag and specify the orthography used for Silesian.

[vxern]

The flag used for Silesia is the one that was used for the general Silesian region and/or Lower Silesia. The modern Silesian language is spoken in Upper Silesia, and the Upper Silesian flag is used pretty much predominantly used to represent Silesian these days. I'm correcting my mistake.

The updated flag also fixes sizing. The previous flag had dimensions 600x400, which breaks certain pages:

I've also specified which orthography to use for Silesian to prevent us ending up with multiple different orthographies used across the same language. I've specified to use Ślabikŏrzowy Szrajbōnek, which is the de facto orthography (Silesian does not have an official orthography, so we have to make do with what we've got).

[jiru]

Thank you for this pull request, @vxern 🙂

The technical adjustments to the SVG file are welcomed.

As for replacing the "Silesia and Lower Silesia" flag with the "Upper Silesia only" flag, I cannot tell if it’s a good move or not. Could you provide some more hindsight and references on the matter?

As for adding the orthographic variant to the language name:

• I am afraid of the potential clutter because the language name is used in many places in the UI.
• Is Silesian orthography on Tatoeba confusing to a point that we need to display the chosen orthography all over the place? In my opinion, this information could be either guessed by looking at existing sentences, or explicitly told as part of welcome messages or interaction with other contributors.
• You said Ślabikŏrz is the de facto standard. To me, it means pretty much everyone uses it by default. If so, then why do we need to add it to the language name?

[vxern]

Regarding the orthography - I suppose you're right, since it's the de facto, it wouldn't need to be specified that it's Ślabikorz that we're using. Just wanted to prevent potential misunderstandings in the future. Someone could submit sentences in another orthography and then wonder why they're not fine to do so, given it's not written that it's the orthography used.

As for the flag - szl is the language code specifically for Upper Silesian. Thus, we ought to use the Upper Silesian flag to represent it, rather than any other flag. For reference, here are some places where Upper Silesian is represented by the blue-yellow colours: https://youtu.be/IUJLLtMrmCg?si=jwtyHRQUYsh3o3ex https://youtu.be/Nhdlz9MeTr4?si=wKbRYpwuddIW5NtZ https://tvpworld.com/77207969/polish-parliament-recognizes-silesian-as-official-regional-language