Document RAND library.
diff --git a/doc/crypto/RAND_cleanup.pod b/doc/crypto/RAND_cleanup.pod
new file mode 100644
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+++ b/doc/crypto/RAND_cleanup.pod
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+=pod
+
+=head1 NAME
+
+RAND_cleanup - erase the PRNG state
+
+=head1 SYNOPSIS
+
+ #include <openssl/rand.h>
+
+ void RAND_cleanup(void);
+
+=head1 DESCRIPTION
+
+RAND_cleanup() erases the memory used by the PRNG.
+
+=head1 RETURN VALUE
+
+RAND_cleanup() returns no value.
+
+=head1 SEE ALSO
+
+rand(3)
+
+=head1 HISTORY
+
+RAND_cleanup() is available in all versions of SSLeay and OpenSSL.
+
+=cut
