Fix the bug of the metadata of the multi-language site.

[FledgeXu]

Fix: #259

[kelson42]

@rgaudin We should check the Name metadata as well

[FledgeXu]

@kelson42 So far, the value of the Name metadata is the file name.

[kelson42]

@FledgeXu … and it’s wrong. For the SE about French language for example:

• filename should be french.stackexchange.com_mul_all_2023-03.zim
• Name metadata should be french.stackexchange.com_mul_all

Can you please fix these problems as well please?

[FledgeXu]

@kelson42 I just check the Name metadata, it looks right?

[FledgeXu]

I just update the code for the clear logic.

[FledgeXu]

@rgaudin Thanks for your reviews! Although it's not merged, I still learnt a lot.