fix issue with multiple release notes (#452)

<!-- This is an auto-generated comment: release notes by OSS CodeRabbit
-->
### Summary by CodeRabbit

```
- Refactor: Updated `DESCRIPTION_START_TAG` constant to be a string and optimized the `removeContentWithinTags` function in `src/commenter.ts`.
- Documentation: Updated product name from "Professional Version of CodeRabbit" to "CodeRabbit Pro" in README.md and src/review.ts.
- New Feature: Announced that CodeRabbit Pro is now free for open source projects, as reflected in src/review.ts.
```
<!-- end of auto-generated comment: release notes by OSS CodeRabbit -->

README.md

@@ -56,13 +56,13 @@ FAQs, you can refer to the sections below.
 - [Contribute](#contribute)
 - [FAQs](#faqs)
 
-## Professional Version of CodeRabbit
+## CodeRabbit Pro
 
 The professional version of `openai-pr-reviewer` project is now available at
-[coderabbit.ai](http://coderabbit.ai). Building upon our open-source foundation,
-CodeRabbit offers premium features including enhanced context and superior noise
-reduction, dedicated support, and our ongoing commitment to improve code
-reviews.
+[coderabbit.ai](http://coderabbit.ai). Building upon our open source foundation,
+CodeRabbit Pro offers premium features including enhanced context and superior
+noise reduction, dedicated support, and our ongoing commitment to improve code
+reviews. Moreover, CodeRabbit Pro is free for open source projects.
 
 ## Install instructions
 

src/commenter.ts

@@ -24,8 +24,8 @@ export const IN_PROGRESS_START_TAG =
 export const IN_PROGRESS_END_TAG =
   '<!-- end of auto-generated comment: summarize review in progress by OSS CodeRabbit -->'
 
-export const DESCRIPTION_START_TAG = `
-<!-- This is an auto-generated comment: release notes by OSS CodeRabbit -->`
+export const DESCRIPTION_START_TAG =
+  '<!-- This is an auto-generated comment: release notes by OSS CodeRabbit -->'
 export const DESCRIPTION_END_TAG =
   '<!-- end of auto-generated comment: release notes by OSS CodeRabbit -->'
 
@@ -93,7 +93,7 @@ ${tag}`
 
   removeContentWithinTags(content: string, startTag: string, endTag: string) {
     const start = content.indexOf(startTag)
-    const end = content.indexOf(endTag)
+    const end = content.lastIndexOf(endTag)
     if (start >= 0 && end >= 0) {
       return content.slice(0, start) + content.slice(end + endTag.length)
     }
@@ -155,7 +155,7 @@ ${tag}`
         DESCRIPTION_START_TAG,
         DESCRIPTION_END_TAG
       )
-      const newDescription = `${description}${DESCRIPTION_START_TAG}\n${messageClean}\n${DESCRIPTION_END_TAG}`
+      const newDescription = `${description}\n${DESCRIPTION_START_TAG}\n${messageClean}\n${DESCRIPTION_END_TAG}`
       await octokit.pulls.update({
         owner: repo.owner,
         repo: repo.repo,

src/review.ts

@@ -465,7 +465,7 @@ ${SHORT_SUMMARY_END_TAG}
 
 ### CodeRabbit Pro
 
-If you like this project, please support us by purchasing the [Pro version](https://coderabbit.ai). The Pro version has advanced context, superior noise reduction and several proprietary improvements compared to the open source version.
+If you like this project, please support us by purchasing the [Pro version](https://coderabbit.ai). The Pro version has advanced context, superior noise reduction and several proprietary improvements compared to the open source version. Moreover, CodeRabbit Pro is free for open source projects.
 
 </details>
 `