[Indexer/TiDB][EASY] Add pre-requisites to README.

## Description

Explain what needs to be installed to get the MySQL version of the
Indexer working.

## Test plan

Try the steps and make sure they work.

crates/sui-indexer/README.md

@@ -59,26 +59,56 @@ Run this command under `sui/crates/sui-indexer`, which will wipe DB; In case of
 ```sh
 diesel database reset --database-url="<DATABASE_URL>"
 ```
-### Local Development(TiDB)
+
+## Steps to run locally (TiDB)
+
+### Prerequisites
+
+1. Install TiDB
+
+``` sh
+curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh
+```
+
+2. Install a compatible version of MySQL (At the time of writing, this is MySQL 8.0 -- note that 8.3 is incompatible).
+
+``` sh
+brew install mysql@8.0
+```
+
+3. Install a version of `diesel_cli` that supports MySQL (and probably also Postgres). This version of the CLI needs to be built against the version of MySQL that was installed in the previous step (compatible with the local installation of TiDB, 8.0.37 at time of writing).
+
+``` sh
+MYSQLCLIENT_LIB_DIR=/opt/homebrew/Cellar/mysql@8.0/8.0.37/lib/ cargo install diesel_cli --no-default-features --features postgres --features mysql --force
+```
+
+### Run the indexer
+
 1.Run TiDB
+
 ```sh
-curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh
 tiup playground
 ```
+
 2.Verify tidb is running by connecting to it using the mysql client, create database `test`
+
 ```sh
 mysql --comments --host 127.0.0.1 --port 4000 -u root
 create database test;
-``` 
+```
+
 3.DB setup, under `sui/crates/sui-indexer` run:
+
 ```sh
 # an example DATABASE_URL is "mysql://root:password@127.0.0.1:4000/test"
 diesel setup --database-url="<DATABASE_URL> --migration-dir='migrations/mysql'"
 diesel database reset --database-url="<DATABASE_URL> --migration-dir='migrations/mysql'"
 ```
+
 Note that you'll need an existing database for the above to work. Replace `test` with the name of the database created.
 4. run indexer as a writer, which pulls data from fullnode and writes data to DB
+
 ```sh
 # Change the RPC_CLIENT_URL to http://0.0.0.0:9000 to run indexer against local validator & fullnode
 cargo run --bin sui-indexer --features mysql-feature --no-default-features -- --db-url "<DATABASE_URL>" --rpc-client-url "https://fullnode.devnet.sui.io:443" --fullnode-sync-worker --reset-db
-```
+```