Merge pull request #7623 from lichuang/share_rfc

docs: refactor share rfc, add select from db and show tables SQL

Author: BohuTANG

docs/doc/60-contributing/03-rfcs/20220809-share.md

@@ -76,6 +76,8 @@ To support creating and managing shares, Databend provides the following set of
 - Describe Share
 - Show Grants
 - Create Database, Table FROM Share
+- Select data from the Share DB tables
+- Show shared database tables
 
 ### Create Share
 
@@ -210,6 +212,33 @@ Syntax:
 CREATE DATABASE <name> FROM SHARE <provider_tenant>.<share_name>
 ```
 
+
+
+### Select data from the Share DB tables
+
+After tenants have created a database from a shared database, tenants can select data from the shared table like a normal table, before that the providers MUST have permitted access permission to the shared database and table.
+
+Syntax:
+
+```sql
+Select * from <share_db_name>.<table_name>
+```
+
+
+
+### Show shared database tables
+
+After tenants have created a database from a shared database,  tenants can show tables from the shared database, it only outputs the tables which have been permitted to access.
+
+ Syntax:
+
+```sql
+use <share_db_name>;
+show tables;
+```
+
+
+
 ## Example of Using Share with SQL
 
 To create a share using SQL: