Add information on required character sets

[SchrodingersGat]

For each db backend (sqlite / postgres / maria / mysql) we should add a note on the required (or recommended) character encoding.

• Need to research how to specify this for each db backend

Ref: inventree/InvenTree#2392

[matmair]

For MySQL UTF-8 is a good base choice -> the ordering can be a bit wired with that though. Swedish collation helps with that.

[eeintech]

Not an expert here... Any idea what we are looking for?

[matmair]

@eeintech this is somewhat database specific and very very technical. Not sure how fast this info can be found for systems outside of mysql, maybe we should move this further back? We had an issue with this so this FR was created.

[eeintech]

Should we clear the 0.6.0 milestone in that case?

[eeintech]

Removed