docs: update v3.1 mainnet hardfork details

Author: darwintree

docs/general/hardforks/v3.1.md

@@ -46,7 +46,7 @@ Conflux v3.1.0 is a hardfork introducing EVM compatibility changes from Ethereum
 ### Upgrade Notes
 
 1. Replace `pos_config/pos_config.yaml` with the copy shipped in this release. The file is parsed strictly and an old copy will not load, so the node will not start. If you changed paths such as `base.data_dir`, `storage.dir` or `logger.file`, carry them over — those keys are unchanged. `pos_config/genesis_file` is no longer used and can be deleted.
-2. The first start after upgrading will take considerably longer than a normal restart. The shipped `run/testnet.toml` now sets `use_isolated_db_for_mpt_table = true`, and the node rebuilds the latest MPT snapshot once to make that switch. Later restarts are unaffected.
+2. The first start after upgrading will take considerably longer than a normal restart. The shipped `run/hydra.toml` now sets `use_isolated_db_for_mpt_table = true`, and the node rebuilds the latest MPT snapshot once to make that switch. Later restarts are unaffected.
 
 ### CIP List
 
@@ -88,4 +88,10 @@ Conflux v3.1.0 is a hardfork introducing EVM compatibility changes from Ethereum
 | Announcement | [Conflux v3.1.0-testnet Hardfork Upgrade Announcement (August 3, 2026)](https://forum.conflux.fun/t/conflux-v3-1-0-testnet-hardfork-20260803/23981) |
 | Deadlines | <ul><li>**Node Upgrade:** Before epoch number reaches 259240000 (estimated on August 7th 2026)</li><li>**CIP-173 Activation:** When PoS block number reaches 3870720 (estimated on August 8th 2026)</li></ul> |
 
-The mainnet release will be published after the testnet upgrade completes.
+### Mainnet
+
+| Key Information | Details |
+| --- | --- |
+| Release | [Conflux v3.1.0](https://github.com/Conflux-Chain/conflux-rust/releases/tag/v3.1.0) |
+| Announcement | [Conflux v3.1.0 Network Hardfork Upgrade Announcement (August 3, 2026)](https://forum.conflux.fun/t/conflux-v3-1-0-network-hardfork-upgrade-announcement-aug-3-2026/23984) |
+| Deadlines | <ul><li>**Node Upgrade:** Before epoch number reaches 155140000 (estimated on August 25th 2026)</li><li>**CIP-173 Activation:** When PoS block number reaches 3749400 (estimated on August 25th 2026)</li></ul> |