chore(prover): update prover readme - min prover gpu ram from 16gb to…

… 6gb (#1189)

# What 💻 
* Update minimum prover GPU RAM requirements from 16Gb -> 6Gb

# Why ✋
* Because @robik75 is kick ass and
[lowered](matter-labs/era-shivini#27) GPU RAM
requirements from 16Gb -> 6Gb

Co-authored-by: Ramon "9Tails" Canales <emaildoramon@gmail.com>

prover/prover_fri/README.md

@@ -132,7 +132,7 @@ installation as a pre-requisite, alongside these machine specs:
 - CPU: At least 8 physical cores
 - RAM: 16GB of RAM(if you have lower RAM machine enable swap)
 - Disk: 30GB of free disk
-- GPU: 1x Nvidia L4/T4 with 16GB of GPU RAM
+- GPU: 1x Nvidia L4/T4 with 6GB of GPU RAM
 
 1. Install the correct nightly version using command: `rustup install nightly-2023-07-21`
 2. Initialize DB and run migrations: `zk init`