Apostrophe added in README.md (#15431)

* Apostrophe corrected - Update README.md

Apostrophe corrected

* Update README.md

---------

Co-authored-by: Nikola Matić <nikola.matic@ethereum.org>

README.md

@@ -72,7 +72,7 @@ The Solidity documentation is hosted using [Read the Docs](https://docs.solidity
 
 Solidity is still under development. Contributions are always welcome!
 Please follow the
-[Developers Guide](https://docs.soliditylang.org/en/latest/contributing.html)
+[Developer's Guide](https://docs.soliditylang.org/en/latest/contributing.html)
 if you want to help.
 
 You can find our current feature and bug priorities for forthcoming