chore: regenerate README (#263)

This PR was generated using Autosynth. 🌈


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

```
2021-02-25 15:10:24,870 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-recommendations-ai/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-25 15:10:26,365 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/5e8b2365-ec0d-4972-8814-616604f58c8b/targets

- [ ] To automatically regenerate this PR, check this box.

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-recommendations-ai.git",
-        "sha": "886d64d5c2e280c7bbb7892ac87b681921d5cb9c"
+        "sha": "820e95b6a9dd5716a8e1c3ba0aa3046e8b003f2c"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "41a4e56982620d3edcf110d76f4fcdfdec471ac8"
+        "sha": "0199c79b8324fba66476300824aa931788c47e2d"
       }
     }
   ]

README.md

@@ -27,12 +27,12 @@ If you are using Maven, add this to your pom.xml file:
 
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-recommendations-ai:0.3.7'
+compile 'com.google.cloud:google-cloud-recommendations-ai:0.4.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-recommendations-ai" % "0.3.7"
+libraryDependencies += "com.google.cloud" % "google-cloud-recommendations-ai" % "0.4.0"
 ```
 
 ## Authentication