docs: nest site into new directory
fill in troubleshooting
tests: use mockery
bigquery#insert: return & test API errors. fixes #336
Merge pull request #326 from stephenplusplus/spp--docs-in-repo

Expand scope of gh-pages site to include non-API docs
Merge pull request #339 from stephenplusplus/spp--bq-doc-fix

bigquery#insert: return & test API errors. fixes #336
Merge pull request #334 from stephenplusplus/spp--improve-coverage

improve coverage
storage: createReadStream: accept start/end offsets