markdown easy and clear lessons three table and formula

#1.markdown easy and clear lessons three table and formula
##2.table
###2.1table
markdown use pipeline diagram to implement table, the table which can use the emphasis, link and other inline format
following code show a basic table
```
lessons' title | chief content
*** |***
about markdown |overview the advantages and disadvantages of markdown
markdown foundation|the basic syntax, formating text, code, list, link and table, seperation line, trope