File naming convention: You are free to use any name you want for your intructions files.
However if you want an instructions file to be associated to a set, the filename must start with the set number (number-version).
For instance, you could use:

• Instructions.pdf: will not be matched to any set
• 107.pdf: will not be matched to set 107-1
• 107-1.pdf: will be matched to set 107-1
• 107-1-2.pdf: will be matched to set 107-1
• 107-1 Special instructions.pdf: will be matched to set 107-1
• 107-1_Special_instructions.pdf: will be matched to set 107-1