Add aws-sig4 to a list of other middleware

README.org

@@ -58,6 +58,7 @@
     - [[#nohttpresponseexception--due-to-stale-connections][NoHttpResponseException ... due to stale connections**]]
 - [[#tests][Tests]]
 - [[#testimonials][Testimonials]]
+- [[#other-middleware][Other Middleware]]
 - [[#license][License]]
 
 * Branches
@@ -1381,6 +1382,15 @@ Libraries inspired by clj-http:
 - [[https://github.com/mpenet/jet][jet]]
 - [[https://github.com/hiredman/clj-http-lite][clj-http-lite]]
 
+* Other libraries providing middleware
+:PROPERTIES:
+:CUSTOM_ID: other-middleware
+:END:
+
+- [[https://github.com/sharetribe/aws-sig4][aws-sig4]] :: a pure clojure implementation of AWS v4 signature request signing as middleware
+
+(feel free to open a PR or issue if you'd like to add middleware here)
+
 * License
 :PROPERTIES:
 :CUSTOM_ID: h-2de3db75-7a1b-42b8-ad3b-6ef27fc2a5ea