chore: regenerate README (googleapis#379)

This PR was generated using Autosynth. 🌈


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

```
2021-02-22 20:30:18,003 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-resourcemanager/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-22 20:30:19,486 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/972cf32a-4e35-4c90-bb77-82743d8297ba/targets

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

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-resourcemanager.git",
-        "sha": "8b70190b68f1dd813ff05805627c7164f886e5a7"
+        "sha": "ffc993893991945c26b94c6459d35c65d86af29d"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "2414b817065726eae0bc525346c7e874f969369d"
+        "sha": "79ab0b44a2cc7d803d07c107f9faf07729fc4012"
       }
     }
   ]

java-resourcemanager/README.md

@@ -20,7 +20,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>16.3.0</version>
+      <version>16.4.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>