feat(docs): add support for Bitcoin symbol in LaTeX documents

Enhanced document compatibility with Bitcoin symbol for broader
financial documentation needs.

- Added `newunicodechar` package to support Unicode characters.
- Implemented `\DeclareUnicodeCharacter` command to define custom
  Unicode characters.
- Defined `\bitcoinA` command to render the Bitcoin symbol using Unicode
  20BF.

Signed-off-by: Glenn Y. Rolland <glenux@glenux.net>

utils/docs/main.tex

@@ -2,8 +2,25 @@
 
 % Set the document language to English
 \usepackage[english]{babel}
-% \usepackage[utf8]{inputenc}
+\usepackage{newunicodechar}
+
+% Define command \DeclareUnicodeCharacter (which was defined in inputenc for non-utf8 engines)
+\newcommand{\DeclareUnicodeCharacter}[2]{%
+    \begingroup\lccode`|=\string"#1\relax
+    	\lowercase{\endgroup\newunicodechar{|}}{#2}%
+}
+
+\def\bitcoinA{%
+  \leavevmode
+  \vtop{\offinterlineskip %\bfseries
+    \setbox0=\hbox{B}%
+    \setbox2=\hbox to\wd0{\hfil\hskip-.03em
+    \vrule height .3ex width .15ex\hskip .08em
+    \vrule height .3ex width .15ex\hfil}
+    \vbox{\copy2\box0}\box2}}
+
 % \DeclareUnicodeCharacter{21D2}{$\Rightarrow$}
+\DeclareUnicodeCharacter{20BF}{\bitcoinA}
 
 % Adjust page geometry
 \usepackage[