add upgrade redirects (#261)

Author: mongoKart

config/redirects

@@ -14,3 +14,5 @@ raw: ${prefix}/master -> ${base}/upcoming/
 [*-master]: ${prefix}/${version}/fundamentals/data-formats/polymorphism/ -> ${base}/${version}/fundamentals/serialization/polymorphic-objects/
 [*-master]: ${prefix}/${version}/fundamentals/data-formats/bson/ -> ${base}/${version}/fundamentals/bson/
 [*-master]: ${prefix}/${version}/fundamentals/class-mapping/ -> ${base}/${version}/fundamentals/serialization/class-mapping/
+[*-v2.30]: ${prefix}/${version}/upgrade/v2/ -> ${base}/${version}/upgrade/
+[*-v2.30]: ${prefix}/${version}/upgrade/v3/ -> ${base}/${version}/upgrade/