Add Text_format.md

Text_format.md

@@ -0,0 +1,28 @@
+# Line breaks
+**A single press of Enter will not start a new line.** 
+Add two spaces at the end of a line, then press Enter.   
+Put a backslash () `\` at the end of a line, then press Enter.\
+Use the HTML tag `<br>`.<br>
+# Font & Text Emphasis.  
+Text emphasis is an important writing skill. Markdown provides simple ways to apply bold and italic styles.  
+Markdown supports two common text styles: bold and italic.  
+Bold syntax: Wrap text with two asterisks ** or two underscores __.  
+Italic syntax: Wrap text with one asterisk * or one underscore _.  
+Bold and italic syntax: Wrap text wiht three * or _.  
+For example: *Italic*,**Bold**,***Bold and italic***.  
+# Horizontal Rule (HR)  
+In Markdown, the Horizontal Rule is used to add a dividing line, and its usage is very simple.  
+Simply enter three or more identical symbols (*,-,_) on a single line. Spaces between symbols are allowed and will not affect the display.  
+- - -
+___
+* * * 
+# Strikethrough  
+Strikethrough syntax: Wrap text with two tilde marks ~~  
+~~For example~~  
+# Underline 
+Markdown has no native syntax for underlines. You need to use HTML tags instead `<u>`.  
+Syntax: Use the tag `<u>` to wrap the content.  
+<u>Underline text</u>    
+# Footnote
+Footnotes are used to add supplementary notes, explanations or citations to text.  
+[^Footnote]: not only