mruby3.2.md: add fixed CVE list.
- Add `Class#subclasses` method.
- Add `Module#undefined_instance_methods` method.
+
+# CVEs
+
+Following CVEs are fixed.
+
+- [CVE-2022-0481](https://nvd.nist.gov/vuln/detail/CVE-2022-0481)
+- [CVE-2022-0525](https://nvd.nist.gov/vuln/detail/CVE-2022-0525)
+- [CVE-2022-0570](https://nvd.nist.gov/vuln/detail/CVE-2022-0570)
+- [CVE-2022-0614](https://nvd.nist.gov/vuln/detail/CVE-2022-0614)
+- [CVE-2022-0623](https://nvd.nist.gov/vuln/detail/CVE-2022-0623)
+- [CVE-2022-0630](https://nvd.nist.gov/vuln/detail/CVE-2022-0630)
+- [CVE-2022-0717](https://nvd.nist.gov/vuln/detail/CVE-2022-0817)
+- [CVE-2022-1212](https://nvd.nist.gov/vuln/detail/CVE-2022-1212)
+- [CVE-2022-1276](https://nvd.nist.gov/vuln/detail/CVE-2022-1276)
+- [CVE-2022-1286](https://nvd.nist.gov/vuln/detail/CVE-2022-1286)
