[ETCM-202] Update README

Author: Michal Mrozek

README.md

@@ -24,6 +24,24 @@ Example:
 
 Possible networks: `etc`, `eth`, `mordor`, `testnet-internal`
 
+### Command Line Interface
+
+`mantis-cli` is a tool that can be used to:
+ 
+ - generate a new private key
+ ```
+./bin/mantis mantis-cli generate-private-key
+```
+ - derive an address from private key
+```
+./bin/mantis mantis-cli derive-address 00b11c32957057651d56cd83085ef3b259319057e0e887bd0fdaee657e6f75d0
+```
+ - generate genesis allocs (using private keys or addresses)
+```
+(private keys) `./bin/mantis mantis-cli generate-alloc --balance=42 00b11c32957057651d56cd83085ef3b259319057e0e887bd0fdaee657e6f75d0 00b11c32957057651d56cd83085ef3b259319057e0e887bd0fdaee657e6f75d1`
+(addresses) `./bin/mantis mantis-cli generate-alloc --balance=42 --useAddresses 8b196738d90cf3d9fc299e0ec28e15ebdcbb0bdcb281d9d5084182c9c66d5d12`
+```
+
 ### Building the client
 
 #### SBT
@@ -81,7 +99,7 @@ This patch will update the lock files for you.
 
 - `repo.nix`                 : generated by the `sbtix-gen` command and includes only the build dependencies for the project.
 - `project/repo.nix`         : generated by the `sbtix-gen-all` command and includes only the plugin dependencies. Also generates `repo.nix`.
-- `project/project/repo.nix` : generated by the `sbtix-gen-all2` command and includes only the pluginplugin dependencies. Also generates `repo.nix` and `project/repo.nix`.
+- `project/project/repo.nix` : generated by the `sbtix-gen-all2` command and includes only the plugin dependencies. Also generates `repo.nix` and `project/repo.nix`.
 
 ##### error: unsupported argument 'submodules' to 'fetchGit'