Option to add a source control link if `riskassessment` could not find it

[LDSamson]

Just sharing an idea here (not sure how feasible it is to implement):

For example, for package shinyjs the source control link could not be found while it clearly exists, which which leads to a less reliable risk score:

It would be great if we can provide the existing link to the github page manually, and that then the risk score is calculated.

Something similar can be thought of editing other metrics manually, especially if they could not be found automatically.