Update zk_login.md to fix zkey download instructions, add recommended…

… machine specs (#14360)

## Description 

Describe the changes or additions included in this PR.

## Test Plan 

How did you test the new or updated feature?

---
If your changes are not user-facing and not a breaking change, you can
skip the following section. Otherwise, please indicate what changed, and
then add to the Release Notes section as highlighted during the release
process.

### Type of Change (Check all that apply)

- [ ] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

doc/src/build/zk_login.md

@@ -297,15 +297,15 @@ const partialZkLoginSignature = proofResponse as PartialZkLoginSignature;
 
 1. Download two images from from Docker Hub [repository](https://hub.docker.com/repository/docker/mysten/zklogin/general) that are tagged as `prover` and `prover-fe`. 
 
-1. Download the [Groth16 proving key zkey file](https://docs.circom.io/getting-started/proving-circuits/) that will be later used as an argument to run the prover. See [the Ceremony section](#ceremony) for more details on how the proving key was generated.
+1. Download the [Groth16 proving key zkey file](https://docs.circom.io/getting-started/proving-circuits/) that will be later used as an argument to run the prover. See [the Ceremony section](#ceremony) for more details on how the proving key was generated. Please install [git lfs](https://git-lfs.com/) which is needed before downloading the zkey.
 
 ```bash
-curl -O https://github.com/sui-foundation/zklogin-ceremony-contributions/blob/main/phase2/final.zkey
+wget -O - https://raw.githubusercontent.com/sui-foundation/zklogin-ceremony-contributions/main/download-zkey.sh | bash
 ```
 
-   - To verify the correct zkey file is downloaded, you can check the Blake2b hash equals to `060beb961802568ac9ac7f14de0fbcd55e373e8f5ec7cc32189e26fb65700aa4e36f5604f868022c765e634d14ea1cd58bd4d79cef8f3cf9693510696bcbcbce` by running `b2sum final.zkey`.
+   - To verify the correct zkey file is downloaded, you can check the Blake2b hash equals to `060beb961802568ac9ac7f14de0fbcd55e373e8f5ec7cc32189e26fb65700aa4e36f5604f868022c765e634d14ea1cd58bd4d79cef8f3cf9693510696bcbcbce` by running `b2sum zkLogin.zkey`.
 
-1. Run `prover` at `PORT1` with the downloaded zkey. This needs to be run on Linux-based machines (amd64).
+1. Run `prover` at `PORT1` with the downloaded zkey. This needs to be run on Linux-based machines (amd64). Further, we recommended using at least 16 vcpu, preferably an AMD cpu and at least 16gb ram for production use. Whereas 8 vcpu, 8gb ram works for testing (but its not fast).
 
 ```bash
 docker run \
@@ -670,4 +670,4 @@ The following command runs the same signature verify function that is used in Su
 
 ```bash
 $SUI_BINARY keytool zk-login-sig-verify --sig $ZKLOGIN_SIG --tx-bytes $TX_BYTES --provider Google --curr-epoch $EPOCH
-```
+```