Bump for v1.3.2.

Note that v1.3.2 contains only documentation fixes compared to
v1.3.1.  So there is no urgency to update if already on 1.3.1.

include/nng/nng.h

@@ -47,12 +47,10 @@ extern "C" {
 
 // NNG Library & API version.
 // We use SemVer, and these versions are about the API, and
-// may not necessarily match the ABI versions. Right now at
-// version 0, you should not be making any forward compatibility
-// assumptions.
+// may not necessarily match the ABI versions.
 #define NNG_MAJOR_VERSION 1
 #define NNG_MINOR_VERSION 3
-#define NNG_PATCH_VERSION 1
+#define NNG_PATCH_VERSION 2
 #define NNG_RELEASE_SUFFIX "" // if non-empty, this is a pre-release
 
 // Maximum length of a socket address. This includes the terminating NUL.