Warning messages broken in docs

[TomJGooding]

I noticed some warning messages seem to be broken in the documentation, for example in the Usage section:

I thought this might be a simple PR but I'm afraid I'm new to Nuklear and Doxygen! I've included my attempted fixes below but neither seem ideal.

diff --git a/src/HEADER.md b/src/HEADER.md
index 60b2478..f01ac6b 100644
--- a/src/HEADER.md
+++ b/src/HEADER.md
@@ -88,9 +88,20 @@ Also optionally define the symbols listed in the section "OPTIONAL DEFINES"
 below in header and implementation mode if you want to use additional functionality
 or need more control over the library.
 
+<!-- Current broken warning -->
 !!! WARNING
     Every time nuklear is included define the same compiler flags. This very important not doing so could lead to compiler errors or even worse stack corruptions.
 
+<!-- Doxygen warning - matches other header warnings but invalid markdown and adds unwanted '!!!' above -->
+!!! \warning
+    Every time nuklear is included define the same compiler flags. This very important not doing so could lead to compiler errors or even worse stack corruptions.
+
+<br >
+
+<!-- Github warning - valid markdown but doesn't match other header warnings -->
+> [!warning]
+> Every time nuklear is included define the same compiler flags. This very important not doing so could lead to compiler errors or even worse stack corruptions.
+
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