Add render and extend

What's Changed

• note on adding examples to Goldens by @abraithwaite in #37
• Add extend operator by @ejcx in #36
• chore: Update README.md typos and Discord link by @jamesejr in #47
• Fix project, minor parsing bug. by @ejcx in #45
• feat: add kusto scalar functions: now(), toupper(), tolower() by @shellcromancer in #43
• Slight bug with extend, might also exist with project by @ejcx in #44
• Update discord link by @ejcx in #48
• Make extend parsing closer to summarize parsing by @zombiezen in #51
• Add named parameter compile option by @zombiezen in #49
• Add let statement by @zombiezen in #52
• Render by @ejcx in #57

New Contributors

• @abraithwaite made their first contribution in #37
• @jamesejr made their first contribution in #47
• @shellcromancer made their first contribution in #43
• @zombiezen made their first contribution in #51

Full Changelog: https://github.com/runreveal/pql/commits/v0.2.0