Fix misleading ##pedigreeDB=<url> notation in older VCF specifications

PR #88 removed the `<>` from `##pedigreeDB=<url>` in VCFv4.3.tex,
presumably on the grounds that they were merely metasyntactic variable
notation and not intended to appear literally. As some readers still
refer to these older documents, remove the misleading notation here too.

VCFv4.1.tex

@@ -136,7 +136,7 @@ \subsubsection{Pedigree field format}
 \end{verbatim}
 or a link to a database:
 \begin{verbatim}
-##pedigreeDB=<url>
+##pedigreeDB=URL
 \end{verbatim}
 \subsection{Header line syntax}
 The header line names the 8 fixed, mandatory columns. These columns are as follows:
@@ -893,7 +893,7 @@ \subsubsection{Clonal derivation relationships}
 Alternately, if data on the genomes is compiled in a database, a simple pointer can be provided:
 
 \begin{verbatim}
-##pedigreeDB=<url>
+##pedigreeDB=URL
 \end{verbatim}
 
 The most general form of a pedigree line is:

VCFv4.2.tex

@@ -153,7 +153,7 @@ \subsubsection{Pedigree field format}
 \end{verbatim}
 or a link to a database:
 \begin{verbatim}
-##pedigreeDB=<url>
+##pedigreeDB=URL
 \end{verbatim}
 \subsection{Header line syntax}
 The header line names the 8 fixed, mandatory columns. These columns are as follows:
@@ -910,7 +910,7 @@ \subsubsection{Clonal derivation relationships}
 Alternately, if data on the genomes is compiled in a database, a simple pointer can be provided:
 
 \begin{verbatim}
-##pedigreeDB=<url>
+##pedigreeDB=URL
 \end{verbatim}
 
 The most general form of a pedigree line is: