fix: corrected yarn add statement in README.md

[SantiagoDevRel]

#33 (comment)

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[Muhammad-Altabba]

Thanks @SantiagoDevRel for catching this.

[Muhammad-Altabba]

To keep the CHANGELOG.md simple, we put one line for the change and we include the PR number. And any description we would like to associate would be at the PR description (you can edit it).

Suggested change

	- Corrected the `yarn add` statement for the Chainlink web3.js plugin.
	- Previously, the documentation incorrectly stated:
	```
	yarn add @chainsafe/web3.js-chainlink-plugin
	```
	However, the correct yarn statement is:
	```
	yarn add "@chainsafe/web3-plugin-chainlink";
	```
	- Corrected the `yarn add` statement according to the new package name (#34)