README.md: Add export restriction notice for MbedTLS
@@ -237,3 +237,23 @@ A: Here are three:
Use of the name `apps/external` is suggested because that name is included
in the `.gitignore` file and will save you some nuisance when working with
GIT.
+
+# Export restrictions
+
+This distribution includes cryptographic software. The country in which you
+currently reside may have restrictions on the import, possession, use, and/or
+re-export to another country, of encryption software. BEFORE using any encryption
+software, please check your country's laws, regulations and policies concerning
+the import, possession, or use, and re-export of encryption software, to see if
+this is permitted. See <http://www.wassenaar.org/> for more information.
+
+The U.S. Government Department of Commerce, Bureau of Industry and Security (BIS),
+has classified this software as Export Commodity Control Number (ECCN) 5D002.C.1,
+which includes information security software using or performing cryptographic
+functions with asymmetric algorithms. The form and manner of this Apache Software
+Foundation distribution makes it eligible for export under the License Exception ENC
+Technology Software Unrestricted (TSU) exception (see the BIS Export Administration
+Regulations, Section 740.13) for both object code and source code.
+
+The following provides more details on the included cryptographic software:
+https://tls.mbed.org/supported-ssl-ciphersuites.
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