improved wording

Author: mtrezza

CONTRIBUTING.md

@@ -284,10 +284,23 @@ Introducing new [Parse Server configuration][config] parameters requires the fol
 
 ## Versioning
 
-Parse Server follows [semantic versioning](https://semver.org) with syntax `x.y.z` which defines:
-- `x` is the *major* version number which means a *breaking release* that may include changes that are not backwards compatible
-- `y` is the *minor* version number which means a *feature release* that may include new features, improvements or other changes that are backwards compatible
-- `z` is the *patch* version number which means a *patch release* that may include bug fixes that are backwards compatible
+> The following versioning system is applied since Parse Server 5.0.0 and does not necessarily apply to previous releases.
+
+Parse Server follows [semantic versioning](https://semver.org) with a flavor of [calendric versioning](https://calver.org). Semantic versioning makes Parse Server easy to upgrade because breaking changes only occur in major releases. Calendric versioning gives an additional sense of how old a Parse Server release is and allows for future Long Term Support concepts, which Parse Server currently does not provide.
+
+Syntax: `[major]`**.**`[feature]`**.**`[fix]`**-**`[pre-release-label]`
+
+- The `major` version increments every year and may include changes that are *not* backwards compatible.
+- The `feature` version increments during the year and may include new features or improvements of existing features that are backwards compatible.
+- The `fix` version increments during the year and may include bug fixes that are backwards compatible.
+- The `pre-release-label` is optional for pre-release versions such as:
+  - `-alpha` (likely to contain bugs, likely to change in features until release)
+  - `-beta` (likely to contain bugs, no change in features until release)
+  - `-rc0` (unlikely to contain bugs, no change in features until release)
+
+Exceptions:
+- The major version may increment during the year in the unlikely event that a breaking change is so urgent that it cannot wait for the next yearly release. This should be as rare as the planetary alignment of Jupiter and Saturn.
+- Bug fixes of security vulnerabilities are `fix` releases, unless they cause a breaking change, then they are `major` releases.
 
 ## Code of Conduct