Fix outside of buffer access and add docs

src/text_editor/buffer.cpp

@@ -415,8 +415,7 @@ API Int OnCharClassBoundary_GetNextWordEnd(Buffer *buffer, Int pos) {
 }
 
 API Int OnCharClassBoundary_GetPrevWordStart(Buffer *buffer, Int pos) {
-    pos = Clamp(pos, (Int)0, buffer->len);
-    Int i = pos - 1;
+    Int i = Clamp(pos - 1, (Int)0, buffer->len);
 
     if (i >= 0 && GetCharClass(buffer->str[i]) == CharClass_Whitespace) {
         i -= 1;

src/text_editor/ui.cpp

@@ -217,6 +217,41 @@ bool IsOpenBoundary(char c) {
     return result;
 }
 
+/*
+
+Variables that control the default shell for '!' commands
+    DefaultShellWindows - "cmd"
+    DefaultShellUnix    - "bash | sh"
+
+Variables:
+    @ProjectDirectory/build/te
+    @(ProjectDirectory)/build/te
+
+Start of string matchers:
+    !        Execute with default shell
+    !!       Execute hidden with default shell
+    :Command Execute editor command
+        :Set Special case for config stuff
+    http://
+    https://
+    commit
+    py:      @todo, execute in python shell, this will use the python3 shell and pass the rest to it's stdin or maybe as a file
+
+More comprehensive syntax for commands:
+    !{/usr/bin/python,Hidden,Input:Clipboard,Output:Clipboard,WorkingDirectory:@ProjectDirectory,Env:{Thing:asd}}
+
+Otherwise it does filepath parsing:
+    C:/windows/path
+    /unix/path
+    ./it/also/does/linenums:32:3
+    /as/well/as/this/format(111,1)
+    ./thing(10)
+
+
+TODO: need to add '~', but where?
+TODO: on linux find shell on first command and set as default
+
+*/
 ResolvedOpen ResolveOpen(Allocator alo, Window *window, String path, ResolveOpenMeta meta) {
     ResolvedOpen result = {};
     path = Trim(path);