Reorganize directories (#3462)

* 🚚 move files
* 🚚 rename doc folder to docs
* 🚚 rename test folder to tests

docs/examples/operator__equal__nullptr_t.output

@@ -0,0 +1,5 @@
+[1,2,3] == nullptr false
+{"A":"a","B":"b"} == nullptr false
+17 == nullptr false
+"foo" == nullptr false
+null == nullptr true