[FEAT]: Add instructions on how to extract .p12 keys

[glotov4]

Description

When I try to extract keys from .p12, "import' button is inactive and on hover it says "Cannot import because there are no compatible importers" Can you please add information on how to handle it in Linux instructions? I'm using Xubuntu Linux 5.15.0-47-generic #51-Ubuntu SMP Thu Aug 11 07:51:15 UTC 2022 x86_64 GNU/Linux

Additional Information