some little text-sm fixes

- button text size
- dropdown text size
- dropdown toggle icon alignment
- top-nav brand image margin
- added docs part

docs/components/miscellaneous.md

@@ -5,6 +5,19 @@ title: Miscellaneous
 AdminLTE has smaller custom classes that not related to other components are listed here.
 
 
+### Text Size 
+You can change the font sizes with adding to any element `.text-*` e.g. (`.text-sm`).
+- `.text-xs` (0.75rem)
+- `.text-sm` (0.875rem)
+- `.text-md` (1rem)
+- `.text-lg` (1.25rem)
+- `.text-xl` (2rem)
+
+> ##### Tip!
+> You can also add `.text-sm` to `body`, with this you get a complete smaller font on the UI or can you add `.text-sm` to `.main-sidebar` or `.main-header` & `.brand-link`.
+{: .quote-info}
+
+
 ### Dropdown Menu Large
 You can add the `.dropdown-menu-lg` to `.dropdown-menu` for a bigger dropdown menu.