Update for 3.1 release

SECURITY.md

@@ -6,33 +6,34 @@ run mainly in well protected environments. In case it is found that this
 software can be used to violate security mechanisms, developers will try to
 provide patches that mitigate the risk of this misuse.
 
-The current policy is explained in SECURITY.md in the nest-simulator master branch.
-The policy can also be found at <https://github.com/nest/nest-simulator/security/policy>.
+The current policy is explained in SECURITY.md in the nest-simulator
+master branch.  The policy can also be found at
+<https://github.com/nest/nest-simulator/security/policy>.
 
 ## Supported Versions
 
-Generally only the latest version will receive security related updates. In severe
-cases developers may create a backport of the corresponding patch for the
-previous version, if it is also affected.  Currently the following versions are
-being supported with security updates:
+Generally only the latest version will receive security related
+updates. In severe cases developers may create a backport of the
+corresponding patch for the previous version, if it is also affected.
+Currently the following versions are being supported with security
+updates:
 
 | Version  | Supported          |
 | -------- | ------------------ |
-| <=2.16.0 | :x:                |
-| 2.18.x   | :white_check_mark: |
-| 2.20.x   | :heavy_check_mark: |
-| 3.0.x    | :heavy_check_mark: |
+| <=2.18.0 | :x:                |
+| 2.20.1   | :white_check_mark: |
+| 3.x      | :heavy_check_mark: |
 
 ## Reporting a Vulnerability
 
 For reporting a vulnerability please create a security advisory on the
 nest/nest-simulator [Security
-Advisories](https://github.com/nest/nest-simulator/security/advisories) page.
-You need a GitHub account to create an advisory.
-
-Developers will then contact the reporter in a timely manner to assess severity
-and further handling via [Security
-Advisories](https://github.com/nest/nest-simulator/security/advisories) or as
-normal [Issue](https://github.com/nest/nest-simulator/issues) in non-critical
-cases.
+Advisories](https://github.com/nest/nest-simulator/security/advisories)
+page.  You need a GitHub account to create an advisory.
+
+Developers will then contact the reporter in a timely manner to assess
+severity and further handling via [Security
+Advisories](https://github.com/nest/nest-simulator/security/advisories)
+or as normal [Issue](https://github.com/nest/nest-simulator/issues) in
+non-critical cases.