docs: add FACILITATORS.md for set Jovian parameters task

Author: niran

mainnet/2025-12-04-set-jovian-parameters/FACILITATORS.md

@@ -0,0 +1,44 @@
+#### Execute the transaction
+
+### 1. Update repo:
+
+```bash
+cd contract-deployments
+git pull
+cd mainnet/2025-12-04-set-jovian-parameters
+make deps
+```
+
+### 2. Execute
+
+1. Collect outputs from all participating signers.
+1. Concatenate all signatures and export it as the `SIGNATURES`
+   environment variable, i.e. `export
+SIGNATURES="[SIGNATURE1][SIGNATURE2]..."`.
+1. Run the `make execute` command as described below to execute the transaction.
+
+For example, if the quorum is 3 and you get the following outputs:
+
+```shell
+Data:  0xDEADBEEF
+Signer: 0xC0FFEE01
+Signature: AAAA
+```
+
+```shell
+Data:  0xDEADBEEF
+Signer: 0xC0FFEE02
+Signature: BBBB
+```
+
+```shell
+Data:  0xDEADBEEF
+Signer: 0xC0FFEE03
+Signature: CCCC
+```
+
+Execute the transaction:
+
+```bash
+SIGNATURES=AAAABBBBCCCC make execute
+```