Fix readme consistency issues (#652)

* Correct notation for checked checkbox in markdown
* Cleanup image and link notation for consistency
* Syntax highlighting
* Update alt for images and fix incorrect link

Co-authored-by: あく <alleteam@gmail.com>

scripts/ReadMe.md

@@ -44,8 +44,12 @@ Also OB may be damaged, so we've made couple scripts to check and set option byt
 
 Checking option bytes:
 
-	ob.py check
+```bash
+ob.py check
+```
 
 Setting option bytes:
 
-	ob.py set
+```bash
+ob.py set
+```