docs: update CONTRIBUTING.md to include code formatting (#534) (#103)

Co-authored-by: Jeff Ching <chingor@google.com>
Co-authored-by: Jeffrey Rennie <rennie@google.com>

Source-Author: Brian Chen <chenbrian@google.com>
Source-Date: Tue May 12 10:24:59 2020 -0700
Source-Repo: googleapis/synthtool
Source-Sha: 5b48b0716a36ca069db3038da7e205c87a22ed19
Source-Link: googleapis/synthtool@5b48b07

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-storage-nio.git",
-        "sha": "6a9a28105561d4408110d54bb92d4e1099ed7544"
+        "sha": "dc410b9e6d20c296bcce27408b2116b568b51a32"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "98c50772ec23295c64cf0d2ddf199ea52961fd4c"
+        "sha": "5b48b0716a36ca069db3038da7e205c87a22ed19"
       }
     }
   ]