Change XSD schema directory more version agnostic

[rabuono]

Based on the discussion in issue #40.

It would be nicer for development of scripts and tools if the address pointing to the XSD schemas was more version agnostic. This way, a more permanent address can be given for developers, insuring that the latest version of schemas can be fetched, regardless of release version numbering strategy.

In practice, having the link point to a latest or production folder.
For example, instead of:
https://ftp.ebi.ac.uk/pub/databases/ena/doc/xsd/sra_1_5/
Have:
https://ftp.ebi.ac.uk/pub/databases/ena/doc/xsd/latest/

NCBI seems to have a similar approach at:
https://www.ncbi.nlm.nih.gov/viewvc/v1/trunk/sra/doc/
The schemas used in production are in the SRA folder.

[alisha246]

Dear Rafael,

Thank you for your suggestion. We have noted this down for further discussions with the concerned teams to update the links to point to the latest version of XSDs automatically.

Best wishes,
Alisha