Fix installation link in README.md

Why:
    Each time we click the ReScript "installation" link on the README.md, it redirects to an old location leading to "404 page not found".
    We update with the correct link.

Author: Florent Pezet

CHANGELOG.md

@@ -58,6 +58,7 @@
 - Fix the sign of `@inline` bigint constants printed in signatures and error messages, which showed `@inline(-12n)` for `@inline(12n)`. https://github.com/rescript-lang/rescript/pull/8732
 
 #### :memo: Documentation
+-  Fix installation link in README.md. https://github.com/rescript-lang/rescript/pull/9138
 
 #### :nail_care: Polish
 

README.md

@@ -19,7 +19,7 @@
 <h3 align="center">
   <a href="https://rescript-lang.org/docs/manual/latest/introduction">Introduction</a>
   <span> · </span>
-  <a href="https://rescript-lang.org/docs/manual/latest/installation">Installation</a>
+  <a href="https://rescript-lang.org/docs/manual/installation">Installation</a>
   <span> · </span>
   <a href="https://rescript-lang.org/try">Try Online</a>
   <span> · </span>
@@ -49,7 +49,7 @@ ReScript is used by many companies to ship and maintain mission-critical product
 
 ## 🎉 Getting Started
 
-Follow the [Installation Guide](https://rescript-lang.org/docs/manual/latest/installation) to set up a new ReScript project or integrate ReScript into your existing JavaScript project.
+Follow the [Installation Guide](https://rescript-lang.org/docs/manual/installation) to set up a new ReScript project or integrate ReScript into your existing JavaScript project.
 
 For more information on building React apps with ReScript, see the [rescript-react documentation](https://rescript-lang.org/docs/react/latest/installation).