Update section header block to match with VF implementation code examples

[sandykadam]

Reported by @MGS-sails

In WordPress when we use a block to define a section header, the code structure is not the same as it is outlined in VF documentation. Please see below screenshot for the page https://www.ebi.ac.uk/research

The difference in h2 & a tag classes.

[sandykadam]

@kasprzyk-sz Can you please check if this has been fixed, if so please close it.