Add an alternative CLI example for setting up Cartridge topology

[akudiyar]

Only one way of configuring Cartridge topology is described in the tutorials at the moment -- via UI (see https://www.tarantool.io/en/doc/2.5/getting_started/getting_started_cartridge/ and all examples in the https://github.com/tarantool/examples contain the same).

An alternative way of applying topology configuration must be present, via Cartridge API (with the corresponding links to the documentation). Currently, there are no snippets of doing the bootstrap from CLI anywhere.

Example of a snippet which may be added to the getting started page:

$ tarantoolctl connect 'admin:testdb-cluster-cookie@localhost:3301'
connected to localhost:3301
localhost:3301> cartridge = require'cartridge'                                                                                                                                                                                                                                                                                                                                      ---
...

localhost:3301> replicasets = {                                                                                                                                                                                                                                                                                                                                                                   > {
              >     alias = 'app-router',
              >     roles = {'vshard-router'},
              >     join_servers = {{uri = 'localhost:3301'}},
              > },
              > {
              >     alias = 's1-storage',
              >     roles = {'vshard-storage', 'metrics'},
              >     join_servers = {{uri = 'localhost:3302'},{uri = 'localhost:3303'}},
              > },
              > {
              >     alias = 's2-storage',
              >     roles = {'vshard-storage', 'metrics'},
              >     join_servers = {{uri = 'localhost:3304'},{uri = 'localhost:3305'}},
              > }}
---
...

localhost:3301> cartridge.admin_edit_topology({replicasets = replicasets})
---
- error: Peer closed
...

Here the user will have to connect again and do the following:

$ tarantoolctl connect 'admin:testdb-cluster-cookie@localhost:3301'
connected to localhost:3301
localhost:3301> cartridge = require'cartridge'                                                                                                                                                                                                                                                                                                                                      ---
...

localhost:3301> cartridge.admin_bootstrap_vshard()
---
- true
...

Also, it would be very nice to explain what the user sees in the logs after executing these commands.

[Kasen]

I suggest adding examples about each thing this function does. Such as the example of how to bootstrap cluster from scratch, how to add a server to a replicaset, etc.