feat: add 'location' config option

README.md

@@ -1,6 +1,6 @@
 # opencode.nvim
 
-Neovim plugin that toggles an `opencode` terminal in a right-side split.
+Neovim plugin that toggles an `opencode` terminal in a configurable split.
 
 The terminal buffer is kept alive when hidden, so your `opencode` session remains
 available across toggles.
@@ -25,6 +25,7 @@ Using `lazy.nvim`:
   "agj/opencode.nvim",
   opts = {
     width = 0.3,
+    location = "right",
   },
 }
 ```
@@ -57,11 +58,17 @@ show the same session.
 ```lua
 require("opencode").setup({
   width = 0.3,
+  location = "right",
 })
 ```
 
-`width` is the fraction of the screen width used by the terminal window. The
-default is `0.3`. It must be greater than `0` and less than or equal to `1`.
+`width` is the fraction of the screen width used by the terminal window for
+`left` and `right` locations, or the screen height for `top` and `bottom`
+locations. The default is `0.3`. It must be greater than `0` and less than or
+equal to `1`.
+
+`location` controls where the terminal window opens. The default is `"right"`.
+It must be one of `"left"`, `"right"`, `"top"`, or `"bottom"`.
 
 ## Help