[BUG] Wrong URL for PPL documentation on Workbench

[neyp]

Describe the bug

Wrong URL for PPL documentation on Workbench.

To Reproduce
Steps to reproduce the behavior:

1. Go to Workbench
2. Click on 'PPL documentation'

Expected behavior
Load the correct page.

OpenSearch Version
1.3

Dashboards Version
AWS 1.3

[Yury-Fridlyand]

Note, PPL documentation location will be changed in opensearch-project/documentation-website#830.

[joshuali925]

Thanks for letting us know, added a PR #758