Update FreeRDP-Configuration-Manual.markdown

[thejohnha]

I tried running openssl genrsa –out rdp.key 2048 but it gave me an error "Extra arguments given." I believe genrsa was replaced with genpkey so the command is now: openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out rdp.key

Credit to: https://unix.stackexchange.com/questions/415970/openssl-genpkey-algorithm-rsa-vs-genrsa

[thomasphansen]

The original command works just fine - the problem is a typo on "-out": see the differences:

openssl genrsa –out rdp.key 2048
openssl genrsa -out rdp.key 2048

As you can see, the dash before "out" is using a unicode character, which openssl does not understand.
So, the only fix needed is to replace the "–" with a "-", and everyhing will work again... :)