feat: document beta releases expectations

Release-Process.md

@@ -77,6 +77,13 @@ non-patch flow.
 - This branch contains the commits accepted so far that implement the proposal
   in the tracking pull request.
 
+### Beta releases
+
+Beta releases are made from a proposal branch. The version number should be
+incremented to the next minor version with a `-beta` suffix. For example, if the
+next release is `5.0.1`, the beta release would be `5.0.1-beta.0`. The beta
+release should be considered unstable and not suitable for production use.
+
 ### Patch flow
 
 In the patch flow, simple changes are committed to the release branch which

Security.md

@@ -29,6 +29,12 @@ announcement, and may ask for additional information or guidance.
 Report security bugs in third-party modules to the person or team maintaining
 the module.
 
+## Beta releases
+
+Beta releases should be considered unstable and **not suitable for production use**.
+Vulnerabilities found in beta releases should be reported according to the [Reporting a Bug](#reporting-a-bug) section.
+Due to the unstable nature of the branch it is not garanteed that the fix will be released in the next beta release.
+
 ## Disclosure Policy
 
 When the security team receives a security bug report, they will assign it to a