Change heading level h6 to h5
In config UI heading levels on subsections (e.g. 'Devices to publish as accessories switch' in 'Other Accessories') are very small. This makes it difficult to recognize a new subsection and to distinguish between heading and text.

IMO setting heading levels to h5 might offer some better readability.

I've just made a PR #417 with h5. I'd be glad, if it would be accepted.

