Change splitbelow to false

This means that new splits, such as Fugitive, will open above the
current pane rather than below it.

If I don't like it, I'll revert it.

CHANGELOG.md

@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com), but adapt
 
 Instead of grouping changes by tag, they are grouped by the date they are released.
 
+## 21st December 2023
+
+### Changed
+
+* Change `splitbelow` to `false` in Neovim.
+
 ## 19th December 2023
 
 ### Fixed

config/neovim/lua/opdavies/options.lua

@@ -174,7 +174,7 @@ local function set_vim_o()
     signcolumn = "yes:1",
     smartindent = true,
     softtabstop = 2,
-    splitbelow = true,
+    splitbelow = false,
     splitright = true,
     swapfile = false,
     syntax = "on",