Update curl notice in readme
@@ -103,6 +103,12 @@ header files, and link libcurl against the "new" OpenSSL.
libacvp uses compile time macro logic to address differences in the APIs of different OpenSSL
versions.
+Libacvp is designed to work with curl version 7.61.0 or newer. Some operating systems may ship with
+older versions of Curl which are missing certain features that libacvp depends on. While it is
+possible some older versions may work, they are not tested or supported. In this case you should
+either acquire a newer version through your OS package manager if possible or build a newer version
+from source.
+
## Building
