BigQuery: Update sample doc from legacy table reference to a standard sql tablereference.
I couldn't find other samples using the wrong form; the integration tests use the correct form, as expected.
Fixes
@@ -40,7 +40,7 @@ To query existing tables, create a Query and call its Read method:
q := client.Query(`
SELECT year, SUM(number) as num
- FROM [bigquery-public-data:usa_names.usa_1910_2013]
+ FROM ` + "`bigquery-public-data.usa_names.usa_1910_2013`" + `
WHERE name = "William"
GROUP BY year
ORDER BY year
