feat: add terminal mode as a rendered mode by default

## Details

Testing out using this plugin with `fzf-lua` preview. `fzf-lua` uses
terminal mode to interact with `fzf`. Making terminal mode rendered by
default allows the preview windows to be rendered and shouldn't have any
real impact to users.

Author: MeanderingProgrammer

Diff for: README.md

@@ -166,9 +166,9 @@ require('render-markdown').setup({
             ]],
         },
     },
-    -- Vim modes that will show a rendered view of the markdown file
+    -- Vim modes that will show a rendered view of the markdown file, :h mode()
     -- All other modes will be unaffected by this plugin
-    render_modes = { 'n', 'c' },
+    render_modes = { 'n', 'c', 't' },
     anti_conceal = {
         -- This enables hiding any added text on the line the cursor is on
         enabled = true,

Diff for: doc/render-markdown.txt

@@ -213,9 +213,9 @@ Default Configuration ~
                 ]],
             },
         },
-        -- Vim modes that will show a rendered view of the markdown file
+        -- Vim modes that will show a rendered view of the markdown file, :h mode()
         -- All other modes will be unaffected by this plugin
-        render_modes = { 'n', 'c' },
+        render_modes = { 'n', 'c', 't' },
         anti_conceal = {
             -- This enables hiding any added text on the line the cursor is on
             enabled = true,

Diff for: lua/render-markdown/health.lua

@@ -4,7 +4,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '7.6.6'
+M.version = '7.6.7'
 
 function M.check()
     M.start('version')

Diff for: lua/render-markdown/init.lua

@@ -290,9 +290,9 @@ M.default_config = {
             ]],
         },
     },
-    -- Vim modes that will show a rendered view of the markdown file
+    -- Vim modes that will show a rendered view of the markdown file, :h mode()
     -- All other modes will be unaffected by this plugin
-    render_modes = { 'n', 'c' },
+    render_modes = { 'n', 'c', 't' },
     anti_conceal = {
         -- This enables hiding any added text on the line the cursor is on
         enabled = true,