feat: add 'location' config option

doc/opencode.nvim.txt

@@ -13,7 +13,7 @@ CONTENTS                                             *opencode.nvim-contents*
 ===============================================================================
 INTRODUCTION                                           *opencode.nvim*
 
-opencode.nvim toggles an `opencode` terminal in a right-side split.
+opencode.nvim toggles an `opencode` terminal in a configurable split.
 
 The terminal buffer is hidden instead of deleted when closed, so the same
 `opencode` session is shown the next time the window is toggled open.
@@ -38,6 +38,7 @@ Using lazy.nvim: >lua
     "agj/opencode.nvim",
     opts = {
       width = 0.3,
+      location = "right",
     },
   }
 <
@@ -55,7 +56,7 @@ USAGE                                          *opencode.nvim-usage*
 
                                                 *:OpenCodeToggle*
 :OpenCodeToggle
-        Toggle the right-side opencode terminal window.
+        Toggle the opencode terminal window.
 
         If the terminal window is visible, this closes only the window. The
         terminal buffer and running `opencode` process remain alive. If the
@@ -67,6 +68,7 @@ CONFIGURATION                          *opencode.nvim-configuration*
 Call setup with an optional table: >lua
   require("opencode").setup({
     width = 0.3,
+    location = "right",
   })
 <
 
@@ -74,8 +76,14 @@ Options:                                             *opencode.nvim-options*
 
                                                         *opencode.nvim-width*
 width                                                   number, default: 0.3
-        Fraction of the screen width used by the terminal split. Must be
-        greater than 0 and less than or equal to 1.
+        Fraction of the screen width used by the terminal split for left and
+        right locations, or the screen height for top and bottom locations.
+        Must be greater than 0 and less than or equal to 1.
+
+                                                     *opencode.nvim-location*
+location                                                string, default: "right"
+        Side of the screen where the terminal split opens. Must be one of
+        "left", "right", "top", or "bottom".
 
 ===============================================================================
 LICENSE                                      *opencode.nvim-license*