docs/contract: Add references to setting up client node for Cipher

[matevz]

Merge after oasisprotocol/docs#215 is implemented.

[codecov]

Codecov Report

Merging #1150 (3a99b75) into main (e18a28e) will increase coverage by 8.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1150      +/-   ##
==========================================
+ Coverage   67.81%   75.92%   +8.11%     
==========================================
  Files         131      105      -26     
  Lines       11575     9659    -1916     
==========================================
- Hits         7850     7334     -516     
+ Misses       3693     2325    -1368     
+ Partials       32        0      -32     

Impacted Files	Coverage Δ
client-sdk/go/types/address.go
cli/wallet/file/file.go
client-sdk/go/types/token.go
client-sdk/go/config/network.go
cli/wallet/file/secp256k1.go
client-sdk/go/testing/testing.go
client-sdk/go/types/event.go
client-sdk/go/modules/contracts/types.go
client-sdk/go/config/paratime.go
...ent-sdk/go/crypto/signature/secp256k1/secp256k1.go
... and 16 more

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