Directory and TIFF image support added

This is a minor update with 2 important updates.

Directory Support: Now you can mention a/multiple directory path to merge all files inside.
TIFF: TIFF image format support added.

Still, have issues with some TIFF. LZW compression is safe to use with this tool.

Please download the appropriate version for your OS -

• merge2pdf_darwin-amd64 For.Mac.OS.users
• merge2pdf_linux-amd64 For most common desktop linux OS
• merge2pdf_linux-arm64 For linux OS with ARM architecture
• merge2pdf_windows-386.exe For recent windows versions