PDF links on model updates of GCAM 8.2 not working

[amnmalik]

Many of the links on the model updates as part of the newest release here https://github.com/JGCRI/gcam-core/releases/tag/gcam-v8.2 are not working.

[hassaniazi]

SSP update and electricity integration should be working. The other .pdfs are still in the merging or releasing process.