Appearance of tables in documentation pages

[ljwh2]

Several GWAS Catalog documentation pages include tables. These appear nicely formatted in the github preview, but are difficult to read in production UI because of lack of borders, padding and alignment issues.

Some examples are on these pages:

https://www.ebi.ac.uk/gwas/docs/methods/summary-statistics https://www.ebi.ac.uk/gwas/docs/summary-statistics-format https://www.ebi.ac.uk/gwas/docs/related-resources

There is a table on this page that looks better ("Additional sources of summary statistics"), but I don't know how it is generated https://www.ebi.ac.uk/gwas/downloads/summary-statistics