Update Coretime Docs

[Radha]

• With snapshots on Kusama network after it goes live
• Add relevant cross-linking to other Wiki docs with definitions of keywords used -> #5798
• Accessible explanations for new learners/new comers to the ecosystem -> #5798
• Fetch on-chain constants/values wherever applicable -> #5798
• Move "build" content to "build" section and PJS guides to their respective location on the Wiki -> #5811
• Improve RegionX and Lastic docs - add examples for partitioning, interlacing, transfers, and assigning tasks.