docs: update CONTRIBUTING.md to include code formatting (#534)

CONTRIBUTING.md

@@ -99,7 +99,16 @@ mvn -Penable-samples clean verify
     ```
 
 2. [Activate](#profile-activation) the profile.
-3. Define your samples in a normal Maven project in the `samples/` directory
+3. Define your samples in a normal Maven project in the `samples/` directory.
+
+### Code Formatting
+
+Code in this repo is formatted with
+[google-java-format](https://github.com/google/google-java-format).
+To run formatting on your project, you can run:
+```
+mvn com.coveo:fmt-maven-plugin:format
+```
 
 ### Profile Activation
 

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-shared-dependencies.git",
-        "sha": "71644eb2ef7bad219873946a0c869b2d10a7f4ae"
+        "sha": "43ba982b3ef77ea840b1e9a7539f7fc6177a2a6b"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "98c50772ec23295c64cf0d2ddf199ea52961fd4c"
+        "sha": "5b48b0716a36ca069db3038da7e205c87a22ed19"
       }
     }
   ]