DOC: Technical Reference: Add table for text formatting

doc/techref/index.md

@@ -11,6 +11,7 @@ visit the {gmt-docs}`GMT Technical Reference <reference.html>`.
 common_parameters.md
 projections.md
 fonts.md
+text_formatting.md
 patterns.md
 encodings.md
 environment_variables.md

doc/techref/text_formatting.md

@@ -0,0 +1,20 @@
+# GMT Text Formatting
+
+The table below shows how text add to a plot as well as labels of colorbars and
+Cartesian axes can be formatted. Changing the font as well as its color and size
+in this way allows to change those only for specific characters of a longer text. The
+supported fonts are listed at [](/techref/fonts.md).
+
+| Symbol | Behavior |
+| --- | --- |
+| @%*font*%*text*@%%  | Change the font |
+| @;*color*;*text*@;; | Change the font color |
+| @:*size*:*text*@::  | Change the font size |
+| @-*text*@-          | Toggle subscripts on/off |
+| @+*text*@+          | Toggle superscript on/off |
+| @#*text*@#          | Toggle small caps on/off |
+| @\_*text*@\_        | Toggle underline on/off |
+| @!*char1char2*      | Print two characters on top of each other (composite characters, e.g., overstrike) |
+| @\~*text*@\~        | Toggle Greek letters on/off |
+| @@                  | Print the @ sign |
+| @.                  | Print the degree symbol |