Fix typo for ValidateToken documentation (#1610)

src/System.IdentityModel.Tokens.Jwt/JwtSecurityTokenHandler.cs

@@ -722,7 +722,7 @@ public override SecurityToken ReadToken(XmlReader reader, TokenValidationParamet
         /// <exception cref="SecurityTokenReplayDetectedException"><paramref name="token"/> is found in the cache.</exception>
         /// <returns> A <see cref="ClaimsPrincipal"/> from the JWT. Does not include claims found in the JWT header.</returns>
         /// <remarks> 
-        /// Many of the exceptions listed above are not thrown directly from this method. See <see cref="Validators"/> to examin the call graph.
+        /// Many of the exceptions listed above are not thrown directly from this method. See <see cref="Validators"/> to examine the call graph.
         /// </remarks>
         public override ClaimsPrincipal ValidateToken(string token, TokenValidationParameters validationParameters, out SecurityToken validatedToken)
         {