Fix format problem.

[fjcapdevila]

No description provided.

[miketheman]

Can you explain why this is a formatting problem?

[fjcapdevila]

I removed space before colon because of this:
"(...) In modern English-language printing, no space is placed before a colon and a single space is placed after it. (...)" https://en.wikipedia.org/wiki/Colon_(punctuation)

And also removed the word "file", because it is used twice in the same phrase.

[miketheman]

I see - thanks for the reasoning. I think this was meant to be expressed thus:

... to a file named :file:`disk_space.txt`

This is valid Sphinx markup - so an update here might be in order.

[fjcapdevila]

You are right. I don't know why ":file:" markup is not working.

[miketheman]

@fjcapdevila I think it's because of the double ` in the current version.

[fjcapdevila]

Thank you!