Provide the minimum supported Cardano node version for Signers

Author: dlachaume

cardano-min-versions.json

@@ -0,0 +1,9 @@
+{
+  "about": "Minimum supported Cardano node versions for Mithril signers",
+  "network": {
+    "mainnet": "8.7.3",
+    "preprod": "8.7.3",
+    "preview": "8.7.3",
+    "sanchonet": "8.9.0"
+  }
+}

docs/runbook/maintain-cardano-min-versions-file/README.md

@@ -0,0 +1,14 @@
+#  Cardano minimum versions for Signers
+
+## Introduction
+
+The [cardano-min-versions.json](../../../cardano-min-versions.json) file, which specifies the minimum supported versions of the Cardano node for Mithril signers
+This ensures compatibility and functionality across different networks.
+
+## Maintaining the file
+
+When a new a new Cardano node version is released:
+- Verify the Cardano node compatibility with Mithril nodes, especially through the CI process.
+- Depending on the network:
+    - For the stable networks `preview`, `preprod`, and `mainnet`: the minimum supported `cardano-node` version must be updated to be two stable releases behind the current release version.
+    - For the unstable network `sanchonet`: given its current evolving nature, the minimum supported `cardano-node` version may vary from the stable one.

docs/website/root/manual/getting-started/run-signer-node.md

@@ -113,6 +113,32 @@ Note that this guide works on a Linux machine only.
 
 :::
 
+:::info
+
+To verify that your node version is supported, compare the version of your Cardano node with the minimum supported versions listed in the `cardano-min-versions.json` file located at the root of the repository.
+
+First, check the version of your Cardano node by running the following command:
+
+```bash
+cardano-node --version
+```
+
+Then, refer to the minimum supported versions listed in the `cardano-min-versions.json` file, which can be found [here](https://github.com/input-output-hk/mithril/blob/main/cardano-min-versions.json).
+
+You can also fetch the minimum supported version for your network using the command below:
+```bash
+wget -q -O - https://raw.githubusercontent.com/input-output-hk/mithril/main/cardano-min-versions.json | jq -r '.network.**YOUR_CARDANO_NETWORK**'
+```
+
+Here is an example for `preprod`:
+```bash
+wget -q -O - https://raw.githubusercontent.com/input-output-hk/mithril/main/cardano-min-versions.json | jq -r '.network.preprod'
+```
+
+Compare the Cardano node versions, if your node version is equal to or higher than the minimum supported version listed for your network, your Cardano node is supported.
+
+:::
+
 ### Building your own executable
 
 #### Download the source file