Update key-management.md (#1508)
Update key-management.md (#1508)

## Issue Addressed

minor documentation changes in order to have identical command prompts and description below

## Proposed Changes

adjust description "wally" to align with command prompt

## Additional Info

devs might give it a thought whether command line should be "mywallet"
I personally prefer "wally" for minimization reasons =)




sigp/lighthouse,sigp/lighthouse,sigp/lighthouse,sigp/lighthouse