docs: update chat/support links (#3861)

Co-authored-by: Rich Harris <richard.a.harris@gmail.com>

.github/ISSUE_TEMPLATE.md

@@ -1,6 +1,6 @@
 <!--
   👉🏽 Need help or tech support? Please don't open an issue!
-  Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs
+  Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs
 
   ❤️ Rollup? Please consider supporting our collective:
   👉 https://opencollective.com/rollup/donate

.github/ISSUE_TEMPLATE/BUG.md

@@ -12,7 +12,7 @@ about: Something went awry and you'd like to tell us about it.
   Or your issue may be closed.
 
   👉🏽 Need help or tech support? Please don't open an issue!
-  Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs
+  Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs
   
   👉🏽 Is this issue related to an official plugin? Please do not open an issue here, go to the plugins repository instead: https://github.com/rollup/plugins/issues
 

.github/ISSUE_TEMPLATE/DOCS.md

@@ -12,7 +12,7 @@ about: Are the docs lacking or missing something? Do they need some new 🔥 hot
   Or your issue may be closed.
 
   👉🏽 Need help or tech support? Don't open an issue!
-  Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs
+  Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs
 
   ❤️ Rollup? Please consider supporting our collective:
   👉 https://opencollective.com/rollup/donate

.github/ISSUE_TEMPLATE/FEATURE.md

@@ -12,7 +12,7 @@ about: Suggest an idea for this project
   Or your issue may be closed.
 
   👉🏽 Need help or tech support? Please don't open an issue!
-  Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs
+  Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs
 
   ❤️ Rollup? Please consider supporting our collective:
   👉 https://opencollective.com/rollup/donate

.github/ISSUE_TEMPLATE/MODIFICATION.md

@@ -12,7 +12,7 @@ about: Would you like something work differently? Have an alternative approach?
   Or your issue may be closed.
 
   👉🏽 Need help or tech support? Please don't open an issue!
-  Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs
+  Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs
 
   ❤️ Rollup? Please consider supporting our collective:
   👉 https://opencollective.com/rollup/donate

.github/ISSUE_TEMPLATE/SUPPORT.md

@@ -1,11 +1,11 @@
 ---
 name: 🆘 Support, Help, and Advice
-about: 👉🏽 Need help or tech support? Please don't open an issue! Head to https://gitter.im/rollup/rollup or https://stackoverflow.com/questions/tagged/rollupjs.
+about: 👉🏽 Need help or tech support? Please don't open an issue! Head to https://is.gd/rollup_chat or https://stackoverflow.com/questions/tagged/rollupjs.
 
 ---
 
 Hey there! If you need help or tech support then this is not the place to
-ask. Please head to [the Rollup Gitter](https://gitter.im/rollup/rollup)
+ask. Please head to the [Rollup Discord](https://is.gd/rollup_chat)
 instead or post a question to https://stackoverflow.com/questions/tagged/rollupjs.
 
 If you arrived here because you think Rollup's documentation is unclear,

CONTRIBUTING.md

@@ -32,7 +32,7 @@ Anyone can file an expense. If the expense makes sense for the development of th
 
 ## Questions
 
-If you require technical assistance, [Stackoverflow](https://stackoverflow.com/questions/tagged/rollupjs) or [Gitter](https://gitter.im/rollup/rollup) are usually the best places to start.
+If you require technical assistance, [Stackoverflow](https://stackoverflow.com/questions/tagged/rollupjs) or [Discord](https://is.gd/rollup_chat) are usually the best places to start.
 You can also create an [issue](issue) (protip: do a quick search first to see if someone else didn't ask the same question before!).
 
 ## Credits

README.md

@@ -22,8 +22,8 @@
   <a href="https://david-dm.org/rollup/rollup">
     <img src="https://david-dm.org/rollup/rollup/status.svg" alt="dependency status">
   </a>
-  <a href='https://gitter.im/rollup/rollup?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge'>
-    <img src='https://badges.gitter.im/rollup/rollup.svg' alt='Join the chat at https://gitter.im/rollup/rollup'>
+  <a href='https://is.gd/rollup_chat?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge'>
+    <img src='https://img.shields.io/discord/466787075518365708?color=778cd1&label=chat' alt='Join the chat at https://is.gd/rollup_chat'>
   </a>
 </p>
 

docs/08-troubleshooting.md

@@ -2,7 +2,7 @@
 title: Troubleshooting
 ---
 
-If you get stuck, please try discussing the issue on [the Rollup Gitter](https://gitter.im/rollup/rollup) or posting a question to https://stackoverflow.com/questions/tagged/rollupjs. If you've found a bug, or Rollup can't meet your needs, please try [raising an issue](https://github.com/rollup/rollup/issues). Lastly, you may try contacting [@RollupJS](https://twitter.com/RollupJS) on Twitter.
+If you get stuck, please try discussing the issue on the [Rollup Discord](https://is.gd/rollup_chat) or posting a question to https://stackoverflow.com/questions/tagged/rollupjs. If you've found a bug, or Rollup can't meet your needs, please try [raising an issue](https://github.com/rollup/rollup/issues). Lastly, you may try contacting [@RollupJS](https://twitter.com/RollupJS) on Twitter.
 
 ### Avoiding `eval`