feat: add 'f' code_only reg and update variable_explain template

Author: you-n-g

lua/simplegpt/conf.lua

@@ -180,6 +180,9 @@ local M = {
             suffix = "v",
             tpl = "variable_explain.json",
             target = "popup",
+            reg = {
+              f  = format.code_only,
+            },
             opts = { noremap = true, silent = true, desc = "Add Doc For (V)ariable" },
           },
           {

qa_tpls/variable_explain.json

@@ -1 +1 @@
-{"q": "Please create a piece of comments that I can insert into the code.\nThe following content should be included in the comments.\n- The type of the variable\n- A very concrete example of the variable", "t": "You are an expert in programming.\n{% if p %}\nHere are a list of files for reference.\n{{p-}}\n{% endif %}\n\nWe have a file named {{filename}} with content:\n````{{filetype}} \n{{content}}\n````\n\n{%if terminal%}\nHere is some related output from the terminal\n```\n{{terminal}}\n```\n{% endif %}\n\nHere is the location of your current line.\n{{context_line_num}}\n\nYou are focusing on the variable `{% if visual %}{{visual}}{% else %}{{cword}}{% endif %}` in current line\n\n\n{{q}}"}
+{"q": "Please create a piece of comments that I can insert into the code.\nThe following content should be included in the comments.\n- The type of the variable\n- A very concrete example of the variable", "t": "You are an expert in programming.\n{% if p %}\nHere are a list of files for reference.\n{{p-}}\n{% endif %}\n\nWe have a file named {{filename}} with content:\n````{{filetype}} \n{{content}}\n````\n\n{%if terminal%}\nHere is some related output from the terminal\n```\n{{terminal}}\n```\n{% endif %}\n\nHere is the location of your current line.\n{{context_line_num}}\n\nYou are focusing on the variable `{% if visual %}{{visual}}{% else %}{{cword}}{% endif %}` in current line\n\n{{f}}\n\n{{q}}", "f": "No extra explanations.\nNo block quotes. DO NOT include three backticks ``` in the code. Try to keep all the comments (You can modify them to make it better).\nKeep original indent so that we can replace the original code with the newly generated one.\nWhen we have multiple loops of conversations, don't assume that previous modifications have been made. You are still changing the initial version of the code.\nOnly return the signature and the document."}