feat(plugin): add healthcheck (#4)

* feat(healthcheck): add

* docs(readme): add note on health check

Author: kiran94

Diff for: README.md

@@ -15,6 +15,8 @@ use 'kiran94/s3edit.nvim'
 - [`aws`](https://github.com/aws/aws-cli) in your `PATH` and configured
 - Neovim 0.8+
 
+Once installed you can run a health check via `:checkhealth s3edit`
+
 ### Usage
 
 Setup the plugin

Diff for: lua/s3edit/health.lua

@@ -0,0 +1,17 @@
+local M = {}
+
+M.check = function()
+    vim.health.report_start("s3edit.nvim")
+
+    local executable = "aws"
+    local is_executable = vim.fn.executable(executable) > 0
+
+    if is_executable then
+        vim.health.report_ok(executable .. " found!")
+        vim.health.report_info("make sure it is configured. You can check this by running: aws s3 ls")
+    else
+        vim.health.report_error(executable .. " is either not installed or is not within path")
+    end
+end
+
+return M