README.org: adjust headings

README.org

@@ -39,12 +39,8 @@
     The latest version should be shown above with the nexus and maven-central
     badges or can be found on [[https://search.maven.org/#search%7Cga%7C1%7Cg%3A%22net.kemitix%22%20AND%20a%3A%22mon%22][Maven Central]].
 
-** Usage
-   :PROPERTIES:
-   :CUSTOM_ID: usage
-   :END:
 
-*** TypeAlias
+** TypeAlias
    :PROPERTIES:
    :CUSTOM_ID: typealias
    :END:
@@ -131,7 +127,7 @@
    }
    #+END_SRC
 
-*** Maybe
+** Maybe
    :PROPERTIES:
    :CUSTOM_ID: maybe
    :END:
@@ -392,7 +388,7 @@
                                               .toOptional();
       #+END_SRC
 
-*** Result
+** Result
    :PROPERTIES:
    :CUSTOM_ID: result
    :END: