Merge pull request #5227 from EOSIO/read-only-doc

Add missing read-only command line doc

plugins/chain_plugin/chain_plugin.cpp

@@ -234,9 +234,11 @@ void chain_plugin::set_program_options(options_description& cli, options_descrip
          ("key-blacklist", boost::program_options::value<vector<string>>()->composing()->multitoken(),
           "Public key added to blacklist of keys that should not be included in authorities (may specify multiple times)")
          ("read-mode", boost::program_options::value<eosio::chain::db_read_mode>()->default_value(eosio::chain::db_read_mode::SPECULATIVE),
-          "Database read mode (\"speculative\" or \"head\").\n"// or \"irreversible\").\n"
+          "Database read mode (\"speculative\", \"head\", or \"read-only\").\n"// or \"irreversible\").\n"
           "In \"speculative\" mode database contains changes done up to the head block plus changes made by transactions not yet included to the blockchain.\n"
-          "In \"head\" mode database contains changes done up to the current head block.\n")
+          "In \"head\" mode database contains changes done up to the current head block.\n"
+          "In \"read-only\" mode database contains incoming block changes but no speculative transaction processing.\n"
+          )
           //"In \"irreversible\" mode database contains changes done up the current irreversible block.\n")
          ("validation-mode", boost::program_options::value<eosio::chain::validation_mode>()->default_value(eosio::chain::validation_mode::FULL),
           "Chain validation mode (\"full\" or \"light\").\n"