HBASE-20581 Fix documentation about schema updates

Signed-off-by: Balazs Meszaros <balazs.meszaros@cloudera.com>

src/main/asciidoc/_chapters/external_apis.adoc

@@ -186,20 +186,20 @@ creation or mutation, and `DELETE` for deletion.
 
 |/_table_/schema
 |POST
-|Create a new table, or replace an existing table's schema
+|Update an existing table with the provided schema fragment
 |curl -vi -X POST \
   -H "Accept: text/xml" \
   -H "Content-Type: text/xml" \
-  -d '<?xml version="1.0" encoding="UTF-8"?><TableSchema name="users"><ColumnSchema name="cf" /></TableSchema>' \
+  -d '<?xml version="1.0" encoding="UTF-8"?><TableSchema name="users"><ColumnSchema name="cf" KEEP_DELETED_CELLS="true" /></TableSchema>' \
   "http://example.com:8000/users/schema"
 
 |/_table_/schema
 |PUT
-|Update an existing table with the provided schema fragment
+|Create a new table, or replace an existing table's schema
 |curl -vi -X PUT \
   -H "Accept: text/xml" \
   -H "Content-Type: text/xml" \
-  -d '<?xml version="1.0" encoding="UTF-8"?><TableSchema name="users"><ColumnSchema name="cf" KEEP_DELETED_CELLS="true" /></TableSchema>' \
+  -d '<?xml version="1.0" encoding="UTF-8"?><TableSchema name="users"><ColumnSchema name="cf" /></TableSchema>' \
   "http://example.com:8000/users/schema"
 
 |/_table_/schema