syntax: support more single-line comment characters

According to the manual, section 14.2.1 [1], the characters #, |, and *
are also supported as comment characters at the beginning of a line.

[1]: http://ledger-cli.org/3.0/doc/ledger3.html#Comments-and-meta_002ddata

Signed-off-by: Roland Hieber <rohieb@rohieb.name>

syntax/ledger.vim

@@ -54,7 +54,7 @@ syn match ledgerOneCharDirective /^\%(P\|A\|Y\|N\|D\|C\)\s/
 
 syn region ledgerBlockComment start=/^comment/ end=/^end comment/
 syn region ledgerBlockTest start=/^test/ end=/^end test/
-syn match ledgerComment /^;.*$/
+syn match ledgerComment /^[;|*#].*$/
 " comments at eol must be preceded by at least 2 spaces / 1 tab
 syn region ledgerMetadata start=/\%(  \|\t\|^\s\+\);/ skip=/^\s\+;/ end=/^/
     \ keepend contained contains=ledgerTags,ledgerValueTag,ledgerTypedTag