Update MIGRATION.md

Better English wording

MIGRATION.md

 ## Migration From Other Enterprise Search Systems
 
-### Google Search Apliance/Google Mini
+### Google Search Appliance (GSA) / Google Mini
 
-Fess provides GSA-Compatible API.
-To enable this API, set `web.api.gsa=true` to system.properties.
-The endpoint is localhost:8080/gsa. 
-Sending a search query to localhost:8080/gsa/?q=QUERY, GSA-compatible response is returned.
+Fess provides a [Google Search Appliance](https://enterprise.google.com/search/products/gsa.html) (GSA) compatible API. To enable this API, set `web.api.gsa=true` to system.properties. This will enable an enpoint at `<Fess Server Name>:8080/gsa`. When a search query is sent to `<Fess Server Name>:8080/gsa/?q=QUERY`, a GSA compatible response will be returned
 
-For the more details, see [GsaApiManager](https://github.com/codelibs/fess/blob/master/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java) implementation.
+For the more details, see the implementation code in [GsaApiManager](/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java).
 
-### Google Site Search/Google Custom Search
+### Google Site Search (GSS) / Google Custom Search (GSE)
 
-Fess provides Site-Search script to help migrations from GSS/CSE.
-Using Site-Search script, you can replace existing GSS/CSE JavaScript codes with:
+[Fess Site Search](https://github.com/codelibs/fess-site-search) provides [scripts](https://fss-generator.codelibs.org/docs/manual) (see below) to help you migrate from GSS/CSE.
+Using the, you can replace existing GSS/CSE JavaScript codes with:
 
 ```
 <script>
@@ -31,11 +28,11 @@ Using Site-Search script, you can replace existing GSS/CSE JavaScript codes with
 <fess:search></fess:search>
 ```
 
-Fess Site Search works as below:
+An example of Fess Site Search in use is below:
 
-![Fess Site Search](http://fess.codelibs.org/_images/fess-ss-1.png "Fess Site Search")
+![Fess Site Search](https://fess.codelibs.org/_images/fess-ss-1.png "Fess Site Search")
 
 
-### Others
+### More Reading
 
-See [JSON API](http://fess.codelibs.org/11.0/user/json-response.html).
+- [JSON API](https://fess.codelibs.org/12.5/user/json-response.html)