fix: Example TOML config file parsing error (erigontech#8902)

follow  Example TOML config file will cause parsing error
```
erigon git:(devel) ✗ ./build/bin/erigon --config ./config.toml --chain=sepolia
EROR[12-05|12:07:09.029] failed setting config flags from yaml/toml file err="(1, 1): parsing error: keys cannot contain ` character"
(1, 1): parsing error: keys cannot contain ` character
```
after remove ` character works 
```
✗ ./build/bin/erigon --config ./config.toml --chain=sepolia 
INFO[12-05|12:00:17.619] logging to file system                   log dir=data/logs file prefix=erigon log level=info json=false
INFO[12-05|12:00:17.620] Build info                               git_branch=devel git_tag=v2.54.0-91-g47a6ac16d-dirty git_commit=47a6ac16da6de62e589b655bde7936dcdb0eb073
INFO[12-05|12:00:17.620] Starting Erigon on Sepolia testnet... 
INFO[12-05|12:00:17.622] Maximum peer count                       ETH=100 total=100
INFO[12-05|12:00:17.623] starting HTTP APIs                       APIs=eth,debug,net
INFO[12-05|12:00:17.623] torrent verbosity                        level=WRN
INFO[12-05|12:00:19.967] Set global gas cap                       cap=50000000
INFO[12-05|12:00:19.968] [Downloader] Runnning with               ipv6-enabled=true ipv4-enabled=true download.rate=16mb upload.rate=4mb
INFO[12-05|12:00:19.970] Opening Database                         label=chaindata path=/erigon/data/chaindata
INFO[12-05|12:00:19.974] [db] chaindata                           sizeLimit=12TB pageSize=8192
INFO[12-05|12:00:19.975] Re-Opening DB in exclusive mode to apply migrations 
INFO[12-05|12:00:20.025] [db] chaindata                           sizeLimit=12TB pageSize=8192
INFO[12-05|12:00:20.025] Apply migration                          name=db_schema_version5
INFO[12-05|12:00:20.033] Applied migration                        name=db_schema_version5
INFO[12-05|12:00:20.033] Apply migration                          name=txs_begin_end
INFO[12-05|12:00:20.035] Applied migration                        name=txs_begin_end
INFO[12-05|12:00:20.035] Apply migration                          name=txs_v3
INFO[12-05|12:00:20.036] Applied migration                        name=txs_v3
INFO[12-05|12:00:20.036] Updated DB schema to                     version=6.1.0
INFO[12-05|12:00:20.074] [db] chaindata                           sizeLimit=12TB pageSize=8192
INFO[12-05|12:00:20.084] Writing custom genesis block             hash=0x25a5cc106eea7138acab33231d7160d69cb777ee0c2c553fcddf5138993e6dd9
INFO[12-05|12:00:20.085] Initialised chain configuration          config="{ChainID: 11155111, Homestead: 0, DAO: <nil>, Tangerine Whistle: 0, Spurious Dragon: 0, Byzantium: 0, Constantinople: 0, Petersburg: 0, Istanbul: 0, Muir Glacier: 0, Berlin: 0, London: 0, Arrow Glacier: <nil>, Gray Glacier: <nil>, Terminal Total Difficulty: 17000000000000000, Merge Netsplit: 1735371, Shanghai: 1677557088, Cancun: <nil>, Prague: <nil>, Engine: ethash}" genesis=0x25a5cc106eea7138acab33231d7160d69cb777ee0c2c553fcddf5138993e6dd9
INFO[12-05|12:00:20.095] Initialising Ethereum protocol           network=11155111
```

README.md

@@ -264,7 +264,7 @@ of the yaml configuration file and sets the chain to goerli
 Example of setting up TOML config file
 
 ```
-`datadir = 'your datadir'
+datadir = 'your datadir'
 port = 1111
 chain = "mainnet"
 http = true