chore: regenerate README (#287)

This PR was generated using Autosynth. 🌈


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

```
2021-03-23 15:47:40,396 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-recommendations-ai/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-23 15:47:41,351 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/41a0f4e8-33ab-44e6-a303-734374088118/targets

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

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-recommendations-ai.git",
-        "sha": "a8d7de5773a23193b011cdfa43b98dac6d2aed9f"
+        "sha": "fbb42377160890aa67fe898b12777f555f2e8639"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "2c54c473779ea731128cea61a3a6c975a08a5378"
+        "sha": "c84c8f156e09702e1c8946bfb9746e6f5892cf27"
       }
     }
   ]

README.md

@@ -20,7 +20,7 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-recommendations-ai</artifactId>
-  <version>0.4.1</version>
+  <version>0.5.0</version>
 </dependency>
 
 ```