added help2man check in gen-manpages.sh

contrib/devtools/gen-manpages.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# Copyright (c) 2016-2020 The Hush developers
+# Copyright (c) 2016-2021 The Hush developers
 # Released under the GPLv3
 
 TOPDIR=${TOPDIR:-$(git rev-parse --show-toplevel)}
@@ -12,6 +12,15 @@ HUSHTX=${HUSHTX:-$SRCDIR/hush-tx}
 
 [ ! -x $HUSHD ] && echo "$HUSHD not found or not executable." && exit 1
 
+# Check if help2man is installed
+# If not then display error to user and exit
+if ! command -v help2man &> /dev/null
+then
+    echo "help2man could not be found"
+    echo "Please install from your Linux package manager and try again"
+    exit
+fi
+
 # use this if hushd is not running
 #HUSHVER="v3.6.2"
 HUSHVER=$(./src/hushd --version|head -n1|cut -d' ' -f4|cut -d- -f1)