docs: add validator requirement documentation (#318)

docs/orchestrator.md

@@ -73,6 +73,47 @@ qgb orchestrator keys evm list
 
 For more information about the `keys` command, check the `keys` documentation in [here](https://github.com/celestiaorg/orchestrator-relayer/blob/main/docs/keys.md).
 
+### Requirements
+
+To run an orchestrator, you will need to have access to the following:
+
+- Access to your EVM address private key. This latter doesn't need to be funded in any network.
+- A list of bootstrappers for the P2P network. These will be shared by the team for every network we plan on supporting.
+- Access to your consensus node RPC and gRPC ports.
+
+#### Consensus node configuration
+
+Before running the orchestrator, make sure to have the node indexing enabled. To check, open your consensus node `config/config.toml` and check the following section:
+
+```toml
+#######################################################
+###   Transaction Indexer Configuration Options     ###
+#######################################################
+[tx_index]
+
+# What indexer to use for transactions
+#
+# The application will set which txs to index. In some cases a node operator will be able
+# to decide which txs to index based on configuration set in the application.
+#
+# Options:
+#   1) "null"
+#   2) "kv" (default) - the simplest possible indexer, backed by key-value storage (defaults to levelDB; see DBBackend).
+# 		- When "kv" is chosen "tx.height" and "tx.hash" will always be indexed.
+#   3) "psql" - the indexer services backed by PostgreSQL.
+# When "kv" or "psql" is chosen "tx.height" and "tx.hash" will always be indexed.
+indexer = "kv"
+```
+
+Make sure to have the `indexer` set to something other than `"null"`, as seen above where it is set to `"kv"`.
+
+If the indexer was just activated, then, by default, it will not have the previous transactions indexed. And, if you run the orchestrator at the same time, it will try to create the commitments and will fail as the transactions are not indexed.
+
+To solve this, you can do either of the following:
+
+- Re-index by deleting the history and resyncing.
+- Or, connect the orchestrator at first to a public RPC that has indexing activated, and wait for it to catchup and sign up to the last unbonding period. Then, switch the orchestrator to point to your personal validator at the next unbonding period.
+
 ### Start the orchestrator
 
 Now that we have the store initialized, we can start the orchestrator. Make sure you have your Celestia-app node RPC and gRPC accessible, and able to connect to the P2P network bootstrappers.