I think Language Learning Beta is relatively new and must not have existed when the ELL help page was created.
I suggest adding a link to Language Learning Beta to "What topics can I ask about here?"
Here's the relevant section of that page:
Please don’t ask any questions about the following topics. They are out of scope for this site:
Proofreading (for example, "Are there any mistakes?" or "Is this correct?"), unless a source of concern is clearly specified
Questions that can be answered by a quick dictionary lookup (these are off topic on ELL, and there are many free dictionaries available online. If you are asking about the meaning of a word or phrase, you should look up those words in a dictionary first. If you are still confused, be sure to summarize what you found when you did your initial research, and summarize that information in the question.)
"How can I improve my English?" or "What's a good tool for...?" (these are not constructive, because what works well for one learner may not work so well for another)
Translation and non-English languages
Naming, including naming programming variables/classes
Criticism, discussion, and analysis of English literature (you may ask about the meaning of a sentence or passage you find in literature, but be sure you provide sufficient context and cite the source where this material was found)
Requests for resources (we have a Resources List on Meta which you might find useful)
It's the third bullet where I think a link to Language Learning would fit especially well.