api: add pretty exceptions section and simple example

Author: practicalli-johnny

docs/building-api/reitit/index.md

@@ -55,8 +55,8 @@ Each key has a configuration map to define a handler for a specific HTTP method
 (def router
   (ring/ring-handler
    (ring/router
-    [["/" {:get welcome}]]
-    ["/status" {:get status}])))
+    [["/" {:get welcome}]
+     ["/status" {:get status}]])))
 ```
 
 !!! HINT "Passing system configuration argument"
@@ -116,3 +116,40 @@ Handler functions are Clojure functions that take a request map.
       (constantly (response {:application "practicalli awesome-api Service" :status "Alive"})))
     ```
 
+
+## Error Messages
+
+When the router is created from its definition, Reitit will show errors using basic formatting to make them a little more readable.
+
+Using `reitit.dev.pretty/exception` provides human readable and development friendly exception messages.
+
+
+!!! EXAMPLE "Add the reditit.dev library"
+    ```clojure title="deps.edn"
+     :deps
+     {
+      http-kit/http-kit {:mvn/version "2.8.0"}
+      metosin/reitit    {:mvn/version "0.7.0"}
+      metosin/reitit-dev {:mvn/version "0.7.0"} ; human readable exceptions
+     }
+     ;; ---------------------------------------------------------
+    ```
+
+Update the Reitit router configuration to provide an exception that will process errors using `pretty/exception`
+
+!!! EXAMPLE "Add and Exception catch to the router definition"
+    ```clojure
+    (:require
+     [reitit.ring :as ring]
+     [reitit.dev.pretty :as pretty])
+
+    (def router
+      (ring/ring-handler
+       (ring/router
+        [["/" {:get welcome}]
+        ["/status" {:get status}]]
+       {:exception pretty/exception})))
+    ```
+
+
+[Pretty Errors - Reitit Docs](https://cljdoc.org/d/metosin/reitit/0.10.1/doc/basics/error-messages#pretty-errors){target=_blank .md-button}