Update titles of ancestry sub-pages

[ljwh2]

Update the titles & descriptions on the sub-pages linked from this page https://www.ebi.ac.uk/gwas/ancestry as follows:

• Ancestry documentation -> Curation of population descriptors A description of our data extraction and standardisation process

• Ancestry data analysis -> Diversity analysis Distribution of ancestry labels in the GWAS Catalog.

• Author recommendations - NO CHANGE TO TITLE Recommendations for the reporting of GWAS sample metadata.

On this page: https://www.ebi.ac.uk/gwas/docs

• Ancestry documentation -> Curation of population descriptors A description of our sample metadata extraction and standardisation process