* docs(samples): add query external bigtable using temp table

* docs(samples): address feedback

* nit

* docs(samples): address comments

* update projectId

Co-authored-by: Stephanie Wang <[email protected]>

🤖 I have created a release \*beep\* \*boop\* 
---
### Updating meta-information for bleeding-edge SNAPSHOT release.
---


This PR was generated with [Release Please](https://github.com/googleapis/release-please).

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Source-Link: googleapis/synthtool@0762e8e

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-10-06 22:16:04,080 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquery/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-06 22:16:05,141 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

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* docs(samples): add query external bigtable using permanent table

* docs(samples): address feedback

* docs(samples): address comments

autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

🤖 I have created a release \*beep\* \*boop\* 
---
### [1.122.2](https://www.github.com/googleapis/java-bigquery/compare/v1.122.1...v1.122.2) (2020-10-08)


### Bug Fixes

* bigquery exception get reason and message ([#788](https://www.github.com/googleapis/java-bigquery/issues/788)) ([d783c3a](https://www.github.com/googleapis/java-bigquery/commit/d783c3a2baf80da2aa48c6be555904bd3c33bb1a))


### Documentation

* **samples:** add query external bigtable using permanent table ([#764](https://www.github.com/googleapis/java-bigquery/issues/764)) ([257edfc](https://www.github.com/googleapis/java-bigquery/commit/257edfc14ef09efc4474eb5aba08ccf4d7c199c0))
* **samples:** add query external bigtable using temp table ([#763](https://www.github.com/googleapis/java-bigquery/issues/763)) ([fed28c7](https://www.github.com/googleapis/java-bigquery/commit/fed28c78ca4b70569d5148e67522b0f39321b306))
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This PR was generated with [Release Please](https://github.com/googleapis/release-please).