Change formatting of examples

After some discussion back and forth, I've adjusted how to display
the examples and code bock to be of a more REPL-style.
Additionally, a filler character for the "Center Me!" string is added to
illustrate how exactly in centers it.

This commit also adds some small styling changes.

bot/resources/tags/string-formatting.md

@@ -1,25 +1,22 @@
-**String Formatting Mini Language**
-The String Formatting Language in Python is a powerful way to tailor the display of strings and other data structures. This string formatting mini language works for f-strings and .format().
+**String Formatting Mini-Language**
+The String Formatting Language in Python is a powerful way to tailor the display of strings and other data structures. This string formatting mini language works for f-strings and `.format()`.
 
 Take a look at some of these examples!
 ```py
-my_num = 2134234523
-print(f"{my_num:,}")
+>>> my_num = 2134234523
+>>> print(f"{my_num:,}")
+2,134,234,523
 
-my_smaller_num = -30.0532234
-print(f"{my_smaller_num:=09.2f}")
+>>> my_smaller_num = -30.0532234
+>>> print(f"{my_smaller_num:=09.2f}")
+-00030.05
 
-my_str = "Center me!"
-print(f"{my_str:^20}")
+>>> my_str = "Center me!"
+>>> print(f"{my_str:-^20}")
+-----Center me!-----
 
-repr_str = "Spam \t Ham"
-print(f"{repr_str!r}")
-```
-Results:
-```
-2,134,234,523
--00030.05
-      Center me!
+>>> repr_str = "Spam \t Ham"
+>>> print(f"{repr_str!r}")
 'Spam \t Ham'
 ```
 **Full Specification & Resources**