Documentation Parameter references

Hi,

the page about [parameter references ](https://www.commonwl.org/user_guide/topics/parameter-references.html)references in the beginning to an previous example that does not really exist? At least I couldnt find it?

"In a previous example, we extracted a file using the “tar” program. However, that example was very limited because it assumed that the file we were interested in was called “hello.txt"

A link to the previous example would be helpful.

Best,
Thorsten