docs: fill out the design philosophy

docs/explanation/design.md

@@ -1 +1,43 @@
 ## Design Philosophy
+
+First and foremost, this is a color scheme. Making colors work
+well takes precedence over other kinds of functionality.
+
+### UNIX Philosphy
+
+1. Write programs that do one thing and do it well.
+    - Do colors, and do colors well. Other things like displaying the weather
+    are not the responsibility of this plugin.
+1. Write programs to work together.
+    - The full palette is exposed as user options, allowing
+    easy integration with any other kind of tmux configuration.
+1. Write programs to handle text streams, because that is a universal interface.
+    - TMUX is a text based program. Each of the palette options are strings
+    in user options that can be piped into other programs and options.
+
+### Configurability is the root of all evil
+
+Adopted from "[Fish Shell's design philophy](https://fishshell.com/docs/current/design.html)".
+
+Every configuration option in a program is a place where the program is too
+stupid to figure out for itself what the user really wants, and should be
+considered a failure of both the program and the programmer who implemented it.
+
+Rationale: Different configuration options are a nightmare to maintain, since
+the number of potential bugs caused by specific configuration combinations
+quickly becomes an issue. Configuration options often imply assumptions about
+the code which change when reimplementing the code, causing issues with
+backwards compatibility. But mostly, configuration options should be avoided
+since they simply should not exist, as the program should be smart enough to do
+what is best, or at least a good enough approximation of it.
+
+### The law of orthogonality
+
+The set of options that do exist should have a small set of orthogonal features.
+Any situation where two options are related but not identical, one of them
+should be removed, and the other should be made powerful and general enough to
+handle all common use cases of either feature.
+
+Rationale: Related features make the configuration options larger, which makes
+it harder to use. It also increases the size of the source code, making the
+program harder to maintain and update.