Number versions after the Java version, not after palantir's

Up to 2.98.0.6 the version was palantir-java-format's with a build
number appended. The bug fixes made the output differ from upstream, so
following its numbers lost its meaning. From here a version is
<java>.<minor>.<build>: the Java version the formatter is built for,
then a number that moves with every change to the output, then one that
moves with builds that leave the output alone.

The README gets a Versions section that says so, and the palantir
section stops promising a 2.x line and changes waiting for 3.0.

Author: abashev

README.md

@@ -85,16 +85,14 @@ private static void configureResolvedVersionsWithVersionMapping(Project project)
 
 ## Coming from palantir-java-format
 
-- **Same output, except for bug fixes.** 2.98.0.x is the code of palantir-java-format 2.98.0, renamed
-  and rebuilt in the open. Its output is the same except where it fixes a bug, and
-  [Migrate](https://openjavaformat.dev/migrate/) lists those fixes. The fourth number counts builds of
-  an upstream version.
-- **Identical Java packages.** `com.palantir.javaformat.*` stays for the whole 2.x line, so your code
-  and the SPI keep working.
+- **Same output, except for bug fixes.** The formatter is the code of palantir-java-format 2.98.0,
+  renamed and rebuilt in the open. Its output is the same except where it fixes a bug, and
+  [Migrate](https://openjavaformat.dev/migrate/) lists those fixes. Any later change to the output
+  comes with a new minor version, see [Versions](#versions).
+- **Identical Java packages.** `com.palantir.javaformat.*` stays, so your code and the SPI keep
+  working.
 - **One-line migration.** Change the coordinates below. Nothing else.
 
-Other changes to the formatter's output wait for 3.0.
-
 | | palantir-java-format | open-java-format |
 |---|---|---|
 | Maven group | `com.palantir.javaformat` | `dev.openjavaformat` |
@@ -109,8 +107,22 @@ Other changes to the formatter's output wait for 3.0.
 | CLI style flag | `--palantir`, `-palantir` | none: there is one style |
 | Formatter style | `PALANTIR` | `OJF` |
 | Native formatter Gradle property | `palantir.native.formatter` | `openjavaformat.native.formatter` |
-| Java packages | `com.palantir.javaformat.*` | **unchanged in 2.x** |
-| Version numbers | `2.98.0` | `2.98.0.1` |
+| Java packages | `com.palantir.javaformat.*` | **unchanged** |
+| Version numbers | `2.98.0` | `21.<minor>.<build>`, see [Versions](#versions) |
+
+## Versions
+
+A version is three numbers, `<java>.<minor>.<build>`, and each one answers a question of its own.
+
+- **The first is the Java version the formatter is built for**, 21 today. It moves when the minimum
+  Java version moves.
+- **The second counts changes to the output**: a fix in wrapping or alignment, a new rule, a new
+  feature. A newer minor version can reformat code that the previous one left alone.
+- **The third counts builds that leave the output alone**: regressions, internal bugs, dependency
+  and build updates. A newer build formats every file exactly as the previous one did.
+
+Up to 2.98.0.6 the version was palantir-java-format's with a build number appended. Once the bug
+fixes made the output differ from upstream, that numbering lost its meaning.
 
 ## Building and testing locally