Change IDR to ELM in Search, Browse, Classify and Candidates descriptions

[Nicolás Palopoli]

The descriptions of the sections ‘Search’, ‘Browse’, ‘Classify’ and ‘Candidates’ still mention “IDR-related articles”. However, I think the resource is now more focused on ELMs and would be better to replace “IDR-related” to “motif-related” or “ELM-related”.

[Norman Davey]

Changed all to SLiM