Add missing doc comments for more types

[MaxDesiatov]

I noticed that some of our types had no doc comments or had inconsistent formatting, here's a (potentially incomplete) fix for that.

[github-actions[bot]]

Time Change: +235ms (1%)

Total Time: 22,373ms

Test name	Duration	Change
Serialization/Call JavaScript function directly	4ms	+2ms (40%)	🚨
Serialization/Assign JavaScript number directly	4ms	-1ms	🎉
Serialization/Call with JavaScript number directly	5ms	+1ms (24%)	🚨
Serialization/Write JavaScript string directly	6ms	+2ms (39%)	🚨
Serialization/Call with JavaScript string directly	4ms	+1ms (37%)	🚨

View Unchanged

| Test name | Duration | Change | | :--- | :---: | :---: | | Serialization/JavaScript function call through Wasm import | 24ms | +0ms | | Serialization/JavaScript function call through Wasm import with int | 20ms | +0ms | | Serialization/JavaScript function call from Swift | 665ms | +17ms (2%) | | Serialization/Swift Int to JavaScript with assignment | 429ms | +3ms (0%) | | Serialization/Swift Int to JavaScript with call | 2,601ms | +1ms (0%) | | Serialization/JavaScript Number to Swift Int | 678ms | -7ms (1%) | | Serialization/Swift String to JavaScript with assignment | 491ms | +4ms (0%) | | Serialization/Swift String to JavaScript with call | 2,780ms | +7ms (0%) | | Serialization/JavaScript String to Swift String | 6,399ms | +29ms (0%) | | Object heap/Increment and decrement RC | 8,263ms | +174ms (2%) |