docs(samples): adds queryParamsNamed and queryParamsPositional

[steffnay]

Fixes 380

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[JustinBeckwith]

So there are a lot of comments here - but it's not your fault at all. Running repo-tools blasts away a lot of things that shouldn't be changed, so you have to kinda be careful about what gets committed. Apologies!

[codecov]

Codecov Report

Merging #381 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #381   +/-   ##
=======================================
  Coverage   99.44%   99.44%           
=======================================
  Files           4        4           
  Lines         544      544           
  Branches       75       75           
=======================================
  Hits          541      541           
  Misses          2        2           
  Partials        1        1

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[jkwlui]

@JustinBeckwith please force merge this. It has 2 links that links to code in samples/ which doesn't exist yet unless merged to master:

[404] https://github.com/googleapis/nodejs-bigquery/blob/master/samples/queryParamsNamed.js
[404] https://github.com/googleapis/nodejs-bigquery/blob/master/samples/queryParamsPositional.js

[tswast]

LGTM