chore: regenerate README (#265)

This PR was generated using Autosynth. 🌈


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

```
2020-10-19 22:41:25,893 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-os-login/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-19 22:41:26,785 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/06b4e909-47cb-4d22-a294-8d56a92e3da6/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-os-login.git",
-        "sha": "1ede4e3d94247a0a995604899cbd2e4e069fd78c"
+        "sha": "7468a522d0583c092a8241737203b7b90fc0be82"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "b6164c26a111f7f587099d31253abb96b5737bb2"
+        "sha": "6dc98b26a9c823e92fa21455fb6e5862613c49c2"
       }
     }
   ]

README.md

@@ -17,7 +17,7 @@ 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>12.0.0</version>
+      <version>12.1.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -43,8 +43,6 @@ If you are using Maven without BOM, add this to your dependencies:
 
 ```
 
-[//]: # ({x-version-update-start:google-cloud-os-login:released})
-
 If you are using Gradle, add this to your dependencies
 ```Groovy
 compile 'com.google.cloud:google-cloud-os-login:1.1.1'
@@ -53,7 +51,6 @@ If you are using SBT, add this to your dependencies
 ```Scala
 libraryDependencies += "com.google.cloud" % "google-cloud-os-login" % "1.1.1"
 ```
-[//]: # ({x-version-update-end})
 
 ## Authentication