Update changelogs, sdk version, and user-agent for v0.8.1 release (#103)

## Problem

Prepare for v0.8.1 release

## Solution

Update changelogs, sdk version, and the user-agent string to reflect
v0.8.1.

## Type of Change

- [X] Non-code change (docs, etc)

## Test Plan

NA

Author: rohanshah18

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 [comment]: <> (When bumping [pc:VERSION_LATEST_RELEASE] create a new entry below)
 ### Unreleased version
+### v0.8.1
+- Update java generated code for control plane operations 
+
 ### v0.8.0
 - Add support for control plane operations for serverless indexes
 - Add support for collections for pod indexes

README.md

@@ -15,20 +15,20 @@ Maven:
 <dependency>
   <groupId>io.pinecone</groupId>
   <artifactId>pinecone-client</artifactId>
-  <version>0.8.0</version>
+  <version>0.8.1</version>
 </dependency>
 ```
 
 [comment]: <> (^ [pc:VERSION_LATEST_RELEASE])
 
 Gradle:
 ```
-implementation "io.pinecone:pinecone-client:0.8.0"
+implementation "io.pinecone:pinecone-client:0.8.1"
 ```
 
 [comment]: <> (^ [pc:VERSION_LATEST_RELEASE])
 
-Alternatively, you can use our standalone uberjar [pinecone-client-0.8.0-all.jar](https://repo1.maven.org/maven2/io/pinecone/pinecone-client/0.8.0/pinecone-client-0.8.0-all.jar), which bundles the pinecone client and all dependencies together inside a single jar. You can include this on your classpath like any 3rd party JAR without having to obtain the *pinecone-client* dependencies separately.
+Alternatively, you can use our standalone uberjar [pinecone-client-0.8.1-all.jar](https://repo1.maven.org/maven2/io/pinecone/pinecone-client/0.8.1/pinecone-client-0.8.1-all.jar), which bundles the pinecone client and all dependencies together inside a single jar. You can include this on your classpath like any 3rd party JAR without having to obtain the *pinecone-client* dependencies separately.
 
 [comment]: <> (^ [pc:VERSION_LATEST_RELEASE])
 

gradle.properties

@@ -1 +1 @@
-pineconeClientVersion = 0.8.0
+pineconeClientVersion = 0.8.1

src/main/java/io/pinecone/PineconeClientConfig.java

@@ -135,7 +135,7 @@ private String maskedApiKey() {
     }
 
     public String getUserAgent() {
-        String userAgentLanguage = "lang=java; pineconeClientVersion = v0.8.0";
+        String userAgentLanguage = "lang=java; pineconeClientVersion = v0.8.1";
         return (this.getUsageContext() != null) ?
                 userAgentLanguage + "; usageContext=" + this.getUsageContext() : userAgentLanguage;
     }