chore: regenerate README (googleapis#368)

This PR was generated using Autosynth. 🌈


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

```
2021-02-10 17:08:51,492 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-resourcemanager/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-10 17:08:52,299 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/c26ec160-1c22-4ecf-9808-b4139b3aba6a/targets

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java-resourcemanager/.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-resourcemanager.git",
-        "sha": "77e2385390074117eb704ec89d5e682d0fdf1dea"
+        "sha": "8b70190b68f1dd813ff05805627c7164f886e5a7"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "3816b080296d4d52975079fd26c110dd26ba25af"
+        "sha": "2414b817065726eae0bc525346c7e874f969369d"
       }
     }
   ]

java-resourcemanager/README.md

@@ -48,7 +48,7 @@ If you are using Maven without BOM, add this to your dependencies:
 
 If you are using Gradle 5.x or later, add this to your dependencies
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:16.3.0')
+implementation platform('com.google.cloud:libraries-bom:16.4.0')
 
 compile 'com.google.cloud:google-cloud-resourcemanager'
 ```