Add pylint and black commands to CONTRIBUTING.md

CONTRIBUTING.md

@@ -23,6 +23,15 @@ Some pull request guidelines:
 ## Development Environment
 Instructions for installing a development version of Slither can be found in our [wiki](https://github.com/crytic/slither/wiki/Developer-installation).
 
+## Linters
+
+Several linters and security checkers are run on the PRs.
+
+To run them locally:
+
+- `pylint slither --rconfig pyproject.toml`
+- `black slither --config pyproject.toml`
+
 ## Detectors regression tests
 
 For each new detector, at least one regression tests must be present.