"Source system" documentation updates

[NicoledeGreef]

OP timer

https://openplus.monday.com/boards/4092908516/pulses/6571336591

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Ensure that docs related to "Source system" are up to date:

• https://cat.data.fin.gov.bc.ca/node/12
• https://cat.data.fin.gov.bc.ca/documentation/source-system-0