fix doc

Signed-off-by: Nok <[email protected]>

docs/source/configuration.rst

@@ -6,12 +6,12 @@ Configuration
 ===============
 
 *New in version 0.17.3*
-``pandera`` provides a global config `~pandera.config.PanderaConfig`  is created in 0.16.0.
+``pandera`` provides a global config `~pandera.config.PanderaConfig`.
 
-You can also set it via environment variable, e.g.:
+This configuration can also be set using environment variables. For instance:
 ```
 export PANDERA_VALIDATION_ENABLED=False
 export PANDERA_VALIDATION_DEPTH=DATA_ONLY
 ```
 
-By setting `PANDERA_VALIDATION_ENABLE=True`, the runtime validation will be disable and any `validate` call will return a `None`.
+Runtime data validation incurs a performance overhead. To mitigate this, you have the option to disable validation globally. This can be achieved by setting the environment variable `PANDERA_VALIDATION_ENABLE=False`. When validation is disabled, any `validate` call will return `None`.