Fix admonitions, add missing titles. Minor spelling fixes

Author: avivace

src/Audio.md

@@ -45,7 +45,7 @@ Thus, durations will be expressed from their frequencies: for example, a "256 Hz
 
 The length of APU ticks is not affected by [CGB double speed](<#FF4D — KEY1 (CGB Mode only): Prepare speed switch>), so the APU works just the same regardless of CPU speed.
 
-:::warning
+:::warning Terminology
 
 The Game Boy's APU is actually full of tricky details; this chapter will mostly describe the intended / common behavior, and often paper over bugs & quirks.
 Readers wishing to learn more should read the [APU details](<#Audio Details>) chapter.

src/Power_Up_Sequence.md

@@ -133,7 +133,7 @@ The boot ROM picks a compatibility palette using an ID computed using the follow
 The resulting palettes ID is used to pick 3 palettes out of a table via a fairly complex mechanism.
 The user can override this choice using certain button combinations during the logo animation; some of these manual choices are identical to auto-colorizations, [but others are unique](https://tcrf.net/Notes:Game_Boy_Color_Bootstrap_ROM#Manual_Select_Palette_Configurations).
 
-::: tip Available palettes
+:::tip Available palettes
 
 A table of checksums (and tie-breaker fourth letters when applicable) and the corresponding palettes can be found [on TCRF](https://tcrf.net/Notes:Game_Boy_Color_Bootstrap_ROM#Assigned_Palette_Configurations).
 

src/Timer_and_Divider_Registers.md

@@ -2,7 +2,7 @@
 
 :::tip NOTE
 
-The Timer described below is the built-in timer in the gameboy. It has
+The Timer described below is the built-in timer in the Game Boy. It has
 nothing to do with the MBC3s battery buffered Real Time Clock - that\'s
 a completely different thing, described in
 [Memory Bank Controllers](#MBCs).