added latest version disclaimer

Author: jderochervlk

src/common/Util.res

@@ -79,3 +79,11 @@ module Date = {
     dateTimeFormat("en-US", {"month": "short", "day": "numeric", "year": "numeric"})->format(date)
   }
 }
+
+
+let removeVersionFromPathname = (pathname: string) =>
+  pathname->Stdlib.String.split("/")->Array.filter(s => {
+    let isVersion = s->Stdlib.String.includes("v") && s->Stdlib.String.includes(".")
+    !isVersion
+  })
+  ->Array.join("/")

src/common/Util.resi

@@ -14,3 +14,6 @@ module String: {
 module Date: {
   let toDayMonthYear: Date.t => string
 }
+
+
+let removeVersionFromPathname: string => string

src/layouts/SidebarLayout.res

@@ -133,12 +133,15 @@ module Sidebar = {
         None
       }
 
-    <>
+  let { pathname } = Next.Router.useRouter()
+
+    <>  
       <div
         id="sidebar"
         className={(
           isOpen ? "fixed w-full left-0 h-full z-20 min-w-320" : "hidden "
         ) ++ " md:block md:w-48 md:-ml-4 lg:w-1/5 h-auto md:relative overflow-y-visible bg-white mt-28 md:mt-0"}>
+        
         <aside
           id="sidebar-content"
           className="relative top-0 px-4 w-full block md:pt-10 md:top-[7rem] md:sticky border-r border-gray-20 overflow-y-auto pb-24 h-auto max-h-[calc(100vh-7rem)]">
@@ -150,6 +153,10 @@ module Sidebar = {
             className="md:hidden h-16 flex pt-2 right-4 absolute">
             <Icon.Close />
           </button>
+          <div className="mb-4">
+          <p className="text-11">{React.string("You are viewing an older version of the documentation.")}</p>
+          <a className="text-11 text-fire-30 border-b border-fire" href={`https://rescript-lang.org${pathname->Util.removeVersionFromPathname}`}>{React.string("Go to the latest version.")}</a>
+          </div>
           <div className="flex justify-between">
             <div className="w-3/4 md:w-full"> toplevelNav </div>
           </div>