`printfn` and `fend` are the same project

[Marijan Smetko]

There's a redundancy in readme

rust-command-line-utilities/README.md

Line 69 in dba1260

 - [fend](https://github.com/printfn/fend): "Arbitrary-precision unit-aware calculator" ([Documentation](https://printfn.github.io/fend/documentation)). I prefer this calculator. 

rust-command-line-utilities/README.md

Line 71 in dba1260

 - [printfn](https://github.com/printfn/fend): "Arbitrary-precision unit-aware calculator" 

[Sam Schlinkert]

Whoops, great catch. Fixed in 5021b36