chore: regenerate README (#315)

This PR was generated using Autosynth. 🌈


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

```
2021-05-21 00:40:44,164 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-grafeas/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-05-21 00:40:45,906 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/61bf5acf-950b-4555-a6ba-5563ce98b89a/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-grafeas.git",
-        "sha": "331909a19f01d0d7fa5bcb29716f9741c2b91ab0"
+        "sha": "21f11c1baefa1d03f681c768a5514417f2a408b6"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "4f4b1b9b8d8b52f1e9e4a76165896debce5ab7f1"
+        "sha": "8eae0234a16b26c2ff616d305dbd9786c8b10a47"
       }
     }
   ]

README.md

@@ -17,18 +17,18 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>io.grafeas</groupId>
   <artifactId>grafeas</artifactId>
-  <version>1.1.5</version>
+  <version>1.2.0</version>
 </dependency>
 ```
 
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'io.grafeas:grafeas:1.1.5'
+compile 'io.grafeas:grafeas:1.2.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "io.grafeas" % "grafeas" % "1.1.5"
+libraryDependencies += "io.grafeas" % "grafeas" % "1.2.0"
 ```
 
 ## Authentication