Add LEGACY.Rmd vignette for legacy binary dosage formats (1-4)

Covers the legacy workflow: file format descriptions (1-4), converting
VCF files (vcftobdlegacy), converting GEN files (gentobd), merging
(bdmerge), and reading/applying functions (getbdinfo, bdapply, getsnp,
getvcfinfo, vcfapply, getgeninfo, genapply). All code chunks are
executable with the package example data.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jimb3

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: BinaryDosage
 Title: Creates, Merges, and Reads Binary Dosage Files
-Version: 1.0.0.9018
+Version: 1.0.0.9019
 Authors@R:
     c(person(given = "John",
              family = "Morrison",