Change BP_JVM_VERSION default from 11.* to 11

This will not change buildpack behavior. In the future we would like to change the usage of the config value to accept JVM spec versions like 8 and 11 but not semver matchers for the full openjdk vesion. This new default will work in both cases.

Also changes documentation to recommend values like 8 or 11 instead of 8.* or 11.*.

Signed-off-by: Emily Casey <ecasey@vmware.com>

README.md

@@ -32,7 +32,7 @@ The buildpack will do the following if a JRE is requested:
 ## Configuration
 | Environment Variable | Description
 | -------------------- | -----------
-| `$BP_JVM_VERSION` | Configure a specific JDK or JRE version.  This value must _exactly_ match a version available in the buildpack so it's best to use a wildcard such as `8.*`.  Since the buildpack only ships a single version of each supported line (e.g. `8.*`, `11.*`, `14.*`) updates to the buildpack can change the version of the JDK or JRE.  In order to hold the JDK and JRE versions stable, the buildpack version itself must be stable.<p/>Buildpack releases (and the dependency versions for each release) can be found [here][bpv].  Few users will use this buildpack directly, instead consuming a language buildpack like `paketo-buildpacks/java` who's releases (and the individual buildpack versions and dependency versions for each release) can be found [here](https://github.com/paketo-buildpacks/java/releases).  Finally, some users will will consume builders like `paketobuildpacks/builder:base` who's releases can be found [here](https://hub.docker.com/r/paketobuildpacks/builder/tags?page=1&name=base).  To determine the individual buildpack versions and dependency versions for each builder release use the [`pack inspect-builder <image>`](https://buildpacks.io/docs/reference/pack/pack_inspect-builder/) functionality.
+| `$BP_JVM_VERSION` | Configure the JVM version (e.g. `8`, `11`, `15`).  The buildpack will download JDK and JRE assets that are compatible with this version of the JVM specification.  Since the buildpack only ships a single version of each supported line, updates to the buildpack can change the exact version of the JDK or JRE.  In order to hold the JDK and JRE versions stable, the buildpack version itself must be stable.<p/><p/>Buildpack releases (and the dependency versions for each release) can be found [here][bpv].  Few users will use this buildpack directly, instead consuming a language buildpack like `paketo-buildpacks/java` who's releases (and the individual buildpack versions and dependency versions for each release) can be found [here](https://github.com/paketo-buildpacks/java/releases).  Finally, some users will will consume builders like `paketobuildpacks/builder:base` who's releases can be found [here](https://hub.docker.com/r/paketobuildpacks/builder/tags?page=1&name=base).  To determine the individual buildpack versions and dependency versions for each builder release use the [`pack inspect-builder <image>`](https://buildpacks.io/docs/reference/pack/pack_inspect-builder/) functionality.
 | `$BPL_JVM_HEAD_ROOM` | Configure the percentage of headroom the memory calculator will allocated.  Defaults to `0`.
 | `$BPL_JVM_LOADED_CLASS_COUNT` | Configure the number of classes that will be loaded at runtime.  Defaults to 35% of the number of classes.
 | `$BPL_JVM_THREAD_COUNT` | Configure the number of user threads at runtime.  Defaults to `250`.

buildpack.toml

@@ -47,7 +47,7 @@ launch      = true
 [[metadata.configurations]]
 name        = "BP_JVM_VERSION"
 description = "the Java version"
-default     = "11.*"
+default     = "11"
 build       = true
 
 [[metadata.configurations]]