Update the PR process doc with 2 reviewers and a new reviewer team

[manuroe]

We are going to have 2 reviewers per PR to improve the review quality.

[github-actions]

Unit Test Results

114 files  ±0  114 suites  ±0   1m 24s ⏱️ -9s
202 tests ±0  202 ✔️ ±0  0 💤 ±0  0 ❌ ±0 
678 runs  ±0  678 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 1b387c8. ± Comparison against base commit a521824.

[ouchadam]

FWIW buildkite failed due to a dependency related network issue

* What went wrong:
--
  | A problem occurred configuring root project 'workdir'.
  | > Could not resolve all files for configuration ':classpath'.
  | > Could not download commons-collections-3.2.2.jar (commons-collections:commons-collections:3.2.2)
  | > Could not get resource 'https://plugins.gradle.org/m2/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar'.
  | > Could not GET 'https://repo.gradle.org/artifactory/jcenter/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar'. Received status code 409 from server: Conflict