minor typos in project page

[Josh Soref]

the project page [1] says:

> 10 years anniversary

Better:

"10 year anniversary"

> If you example requires large files,

Correct:

"If your example requires large files,"

Thanks for your attention.

[1] https://www.gnu.org/software/parallel/

p.s. I like parallel and am considering applying it to a current task,
hence the quick look into the project's current status.