Incorrect `#this` and `#root` variable examples in SpEL documentation

[mhalbritter]

There is something wrong or incomplete in the SpEL documentation.

• SimpleEvaluationContext.forReadOnlyDataAccess() doesn't compile. I think that should be SimpleEvaluationContext.forReadOnlyDataBinding().build().
• The "following example" has no mention of #root.

The following examples show how to use the #this and #root variables:

[sbrannen]

Thanks for bringing that to our attention, @mhalbritter. 👍

I've fixed those errors (as well as some others that I noticed in the process) and added a new example using #root.

See the 6.1.2 snapshot reference docs.

[mhalbritter]

Thanks Sam!