document undefined behavior related to authMechanismProperties

Author: rcsanchez97

src/libmongoc/doc/mongoc_uri_t.rst

@@ -113,7 +113,7 @@ Authentication Options
 Constant                                   Key                               Description
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 MONGOC_URI_AUTHMECHANISM                   authmechanism                     Specifies the mechanism to use when authenticating as the provided user. See :doc:`Authentication <authentication>` for supported values.
-MONGOC_URI_AUTHMECHANISMPROPERTIES         authmechanismproperties           Certain authentication mechanisms have additional options that can be configured. These options should be provided as comma separated option_key:option_value pair and provided as authMechanismProperties.
+MONGOC_URI_AUTHMECHANISMPROPERTIES         authmechanismproperties           Certain authentication mechanisms have additional options that can be configured. These options should be provided as comma separated option_key:option_value pair and provided as authMechanismProperties. Specifying the same option_key multiple times has undefined behavior.
 MONGOC_URI_AUTHSOURCE                      authsource                        The authSource defines the database that should be used to authenticate to. It is unnecessary to provide this option the database name is the same as the database used in the URI.
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