chore: regenerate README (#515)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-06-03 15:29:38,547 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-kms/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-03 15:29:39,817 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/25b9d646-84dd-4fa5-9e2b-d7bd4d216efb/targets

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.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-kms.git",
-        "sha": "d40768ff45ecbbd9de8091989a84b6f0118ee2f0"
+        "sha": "0e60a579c7e0ca93b42afd1787654be42203f4dc"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "c3e41da0fa256ad7f6b4bc76b9d069dedecdfef4"
+        "sha": "811d20bc0b00c09773dfc74ac2baaf1286e943b7"
       }
     }
   ]

README.md

@@ -52,12 +52,12 @@ compile 'com.google.cloud:google-cloud-kms'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-kms:1.42.0'
+compile 'com.google.cloud:google-cloud-kms:1.42.1'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-kms" % "1.42.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-kms" % "1.42.1"
 ```
 
 ## Authentication