Update README.md

Author: Hanbing Leng

README.md

@@ -5,3 +5,26 @@ A discord bot helps groups with coding practicing and note taking.
 ## Dependency
 - [Go 1.12.1+](https://golang.org/dl/)
 - [sqlite](https://www.sqlite.org/download.html)
+
+## DB Schema
+
+**user**(uid, dcid, uname, fname, lname, createts)
+
+**problem**(pid, pname)
+
+**user_problem**(upid, uid, pid, ts, note)
+
+## Usage
+
+```
+!solved <pname> [-m <msg>]            Record the problem solved with the option to take notes
+!show <uname> [-a]                    Show the problems solved today by given username 
+                                      and show all entries when -a specified
+TODO:
+!count <uname> [-a]
+!noteshow <uname> [-p <pname>]
+!graph <uname>
+!help <pname>
+!today
+!libraryhours
+```