chore: regenerate README (#211)

This PR was generated using Autosynth. 🌈


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

```
2021-03-23 15:48:19,830 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-aiplatform/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-23 15:48:20,837 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/ce5bf427-4202-408d-8306-e4c2cbf78881/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-aiplatform.git",
-        "sha": "2602782f596e6df8b2081ac74359c3c7fa5d1593"
+        "sha": "9d6761d6670ed600eefa539b0afe70128cbe2d92"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79c8dd7ee768292f933012d3a69a5b4676404cda"
+        "sha": "c84c8f156e09702e1c8946bfb9746e6f5892cf27"
       }
     }
   ]

README.md

@@ -19,7 +19,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
   <dependency>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-aiplatform</artifactId>
-    <version>0.3.0</version>
+    <version>0.4.0</version>
   </dependency>
 
 ```
@@ -30,7 +30,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-aiplatform</artifactId>
-  <version>0.3.0</version>
+  <version>0.4.0</version>
 </dependency>
 
 ```
@@ -43,12 +43,12 @@ compile 'com.google.cloud:google-cloud-aiplatform'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-aiplatform:0.3.0'
+compile 'com.google.cloud:google-cloud-aiplatform:0.4.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-aiplatform" % "0.3.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-aiplatform" % "0.4.0"
 ```
 
 ## Authentication