Set INFO Description in VCF Header

[Daniel Cook]

Is it possible to set the Description in the VCF Header?

e.g.:

Change 'calculated by self of overlapping values in column 5 from test_vcf.bed.gz' to something more meaningful.

##INFO=<ID=distance_from_variant_mean,Number=1,Type=Float,Description="calculated by self of overlapping values in column 5 from test_vcf.bed.gz">

[Brent Pedersen]

This is often requested, e.g.:
https://github.com/brentp/vcfanno/issues/63
and:
https://github.com/brentp/vcfanno/issues/65
but I've been hesitant to add it because it adds complexity for the
user for something that could be accomplished with sed.

I'll have a look at adding this for the next release.

-Brent