Updating the migration guide

Author: MaxGekk

docs/sql-migration-guide-upgrade.md

@@ -15,7 +15,7 @@ displayTitle: Spark SQL Upgrading Guide
 
   - Since Spark 3.0, the `from_json` functions supports two modes - `PERMISSIVE` and `FAILFAST`. The modes can be set via the `mode` option. The default mode became `PERMISSIVE`. In previous versions, behavior of `from_json` did not conform to either `PERMISSIVE` nor `FAILFAST`, especially in processing of malformed JSON records. For example, the JSON string `{"a" 1}` with the schema `a INT` is converted to `null` by previous versions but Spark 3.0 converts it to `Row(null)`.
 
-  - In Spark version 2.4 and earlier, JSON data source and the `from_json` function produced `null`s if there is no valid root JSON token in its input (` ` for example). Since Spark 3.0, such input is treated as a bad record and handled according to specified mode. For example, in the `PERMISSIVE` mode the ` ` input is converted to `Row(null, null)` if specified schema is `key STRING, value INT`. 
+  - In Spark version 2.4 and earlier, the `from_json` function produces `null`s if there is no valid root JSON token in its input (` ` for example). Since Spark 3.0, such input is treated as a bad record and handled according to specified mode. For example, in the `PERMISSIVE` mode the ` ` input is converted to `Row(null, null)` if specified schema is `key STRING, value INT`. 
 
   - The `ADD JAR` command previously returned a result set with the single value 0. It now returns an empty result set.