Add examples for FSharp.Core.Result module functions (#12148)

* Add examples for FSharp.Core.Result module functions

* Update result.fsi

Co-authored-by: Kevin Ransom (msft) <[email protected]>
Co-authored-by: Don Syme <[email protected]>

Author: 3 people

src/fsharp/FSharp.Core/result.fsi

@@ -16,8 +16,14 @@ namespace Microsoft.FSharp.Core
         /// <param name="result">The input result.</param>
         ///
         /// <returns>A result of the input value after applying the mapping function, or Error if the input is Error.</returns>
-        /// 
-        /// <example-tbd></example-tbd>
+        ///
+        /// <example>
+        /// <code lang="fsharp">
+        /// Ok 1 |> Result.map (fun x -> "perfect") // evaluates to Ok "perfect"
+        ///
+        /// Error "message" |> Result.map (fun x -> "perfect") // evaluates to Error "message"
+        /// </code>
+        /// </example>
         [<CompiledName("Map")>]
         val map : mapping:('T -> 'U) -> result:Result<'T, 'TError> -> Result<'U, 'TError>
 
@@ -27,8 +33,14 @@ namespace Microsoft.FSharp.Core
         /// <param name="result">The input result.</param>
         ///
         /// <returns>A result of the error value after applying the mapping function, or Ok if the input is Ok.</returns>
-        /// 
-        /// <example-tbd></example-tbd>
+        ///
+        /// <example>
+        /// <code lang="fsharp">
+        /// Ok 1 |> Result.mapError (fun x -> "bar") // evaluates to Ok 1
+        ///
+        /// Error "foo" |> Result.mapError (fun x -> "bar") // evaluates to Error "bar"
+        /// </code>
+        /// </example>
         [<CompiledName("MapError")>]
         val mapError: mapping:('TError -> 'U) -> result:Result<'T, 'TError> -> Result<'T, 'U>
 
@@ -39,7 +51,20 @@ namespace Microsoft.FSharp.Core
         /// <param name="result">The input result.</param>
         ///
         /// <returns>A result of the output type of the binder.</returns>
-        /// 
-        /// <example-tbd></example-tbd>
+        ///
+        /// <example>
+        /// <code lang="fsharp">
+        /// let tryParse (input: string) =
+        ///     match System.Int32.TryParse input with
+        ///     | true, v -> Ok v
+        ///     | false, _ -> Error "couldn't parse"
+        ///     
+        /// Error "message" |> Result.bind tryParse // evaluates to Error "message"
+        ///
+        /// Ok "42" |> Result.bind tryParse // evaluates to Ok 42
+        ///
+        /// Ok "Forty-two" |> Result.bind tryParse // evaluates to Error "couldn't parse"
+        /// </code>
+        /// </example>
         [<CompiledName("Bind")>]
         val bind: binder:('T -> Result<'U, 'TError>) -> result:Result<'T, 'TError> -> Result<'U, 'TError>