Improve the docs and fix number to string

[nicu-chiciuc]

I was reading the docs and I wanted to fix

  const q1 = await e.str("Hello world!").run(client);
  // number

since the inferred type is actually the string literal "Hello world!". But I thought that writing "Hello world!" instead of number seems confusing. So I thought that maybe using an addition so that the inferred type is string is a better idea.

Also I've added run() at the end of the code since I was expecting the code to run something by itself without me having to write run() afterwards. But this is debatable so I can undone the change.

[edgedb-cla]

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