Add section on changing rpc providers

README.md

@@ -19,3 +19,18 @@ If you have any suggestions, want to contribute or want to chat, please join [ou
 ```
 node test.js projects/pangolin/index.js
 ```
+
+## Changing RPC providers
+If you want to change RPC providers because you need archive node access or because the default ones don't work well enough you can do so by creating an `.env` file and filling it with the env variables to overwrite:
+```
+ETHEREUM_RPC="..."
+BSC_RPC="..."
+POLYGON_RPC="..."
+FANTOM_RPC="..."
+ARBITRUM_RPC="..."
+OPTIMISM_RPC="..."
+XDAI_RPC="..."
+HARMONY_RPC="..."
+```
+
+The name of each rpc is `{CHAIN-NAME}_RPC`, and the name we use for each chain can be found [here](https://github.com/DefiLlama/defillama-sdk/blob/master/src/general.ts#L33)