readme: correct upgrade argument for :search/outdated

Signed-off-by: Brian Brunner <Brian.brunner.bb@gmail.com>

README.md

@@ -354,7 +354,7 @@ Tools to search through code and libraries
 * `-M:search/errors` [clj-check](https://github.com/athos/clj-check.git) - search each namespace and report compilation warnings and errors
 * `-M::search/unused-vars` [Carve](https://github.com/borkdude/carve) - search code for unused vars and remove them - optionally specifying paths `--opts '{:paths ["src" "test"]}'`
 * `-M:search/libraries` - [find-deps](https://github.com/hagmonk/find-deps) - fuzzy search Maven & Clojars and add deps to deps.edn
-* `-T:search/outdated` -  [liquidz/antq](https://github.com/liquidz/antq) - check for newer versions of libraries, updating `deps.edn` if `:update true` passed as argument
+* `-T:search/outdated` -  [liquidz/antq](https://github.com/liquidz/antq) - check for newer versions of libraries, updating `deps.edn` if `:upgrade true` passed as argument
 
 
 ### Searching library options