[FR] change temp dir (improve documentation)

[raidlman]

Depending on the length of the recorded cast, the png files can quickly grow in number and size. For systems with limited root file systems, converting casts to gif might clog the system by using too much of the available temp space under /tmp.

I figured you can change the temporary directory by setting the TMPDIR environment variable to tell the mktemp command to user another base directory. See here.

It would be nice if this would be included in you docs.

[yangyang5214]

sounds good

[ku1ik]

Try https://github.com/asciinema/agg instead. It doesn't use any tmp space on disk.