chore: regenerate README (#251)

This PR was generated using Autosynth. 🌈


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

```
2020-10-15 22:44:13,048 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-iamcredentials/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-15 22:44:13,974 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/52c5cae6-8a13-457e-933c-555085b64f1b/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-iamcredentials.git",
-        "sha": "5d1dcff343352bef36399891b282f5dca0946cef"
+        "sha": "60d84d5b3b36b9f60e0848468320a60e87982ab7"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "b6164c26a111f7f587099d31253abb96b5737bb2"
+        "sha": "27e0e916cbfdb3d5ff6639b686cc04f78a0b0386"
       }
     }
   ]

README.md

@@ -43,8 +43,6 @@ If you are using Maven without BOM, add this to your dependencies:
 
 ```
 
-[//]: # ({x-version-update-start:google-cloud-iamcredentials:released})
-
 If you are using Gradle, add this to your dependencies
 ```Groovy
 compile 'com.google.cloud:google-cloud-iamcredentials:1.1.3'
@@ -53,7 +51,6 @@ If you are using SBT, add this to your dependencies
 ```Scala
 libraryDependencies += "com.google.cloud" % "google-cloud-iamcredentials" % "1.1.3"
 ```
-[//]: # ({x-version-update-end})
 
 ## Authentication