chore: regenerate README (#122)

This PR was generated using Autosynth. 🌈


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

```
2021-01-07 22:18:29,424 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-dialogflow-cx/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-01-07 22:18:30,378 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/4a31a31e-51ac-4ca1-a574-18f9b6e9a40e/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-dialogflow-cx.git",
-        "sha": "d240e3caa49d0a3007470f4cb83392c5c8278dc4"
+        "sha": "572973b8c6a76ee820394ac61d6aa2d93e4e8d82"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "3f67ceece7e797a5736a25488aae35405649b90b"
+        "sha": "67f09bf301083798e7220137723222eb00b8f88a"
       }
     }
   ]

README.md

@@ -24,10 +24,11 @@ If you are using Maven, add this to your pom.xml file:
 </dependency>
 ```
 
-If you are using Gradle, add this to your dependencies
+If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
 compile 'com.google.cloud:google-cloud-dialogflow-cx:0.5.0'
 ```
+
 If you are using SBT, add this to your dependencies
 ```Scala
 libraryDependencies += "com.google.cloud" % "google-cloud-dialogflow-cx" % "0.5.0"