2: Add solution to Rust track exercise "Hello World".

Created by  9Zb2bmkejrNknawUtr3MKvVstZkVDR8x8ritfgZXKrky  on December 23, 2021
5GTVOUT3IU6HH3EIYEJATQSKAUZS2DBJVYWBD332FE42L5FPGYJQC
In channels
main
Change contents