Update Writing Plugins docs

docs/en/src/installing-plugins.md

@@ -6,7 +6,12 @@ following procedure:
 - Add the following line in `~/.config/xplr/init.lua`
 
   ```lua
-  package.path = os.getenv("HOME") .. '/.config/xplr/plugins/?/src/init.lua'
+  local home = os.getenv("HOME")
+  package.path = home
+  .. "/.config/xplr/plugins/?/src/init.lua;"
+  .. home
+  .. "/.config/xplr/plugins/?.lua;"
+  .. package.path
   ```
 
 - Clone the plugin

docs/en/src/writing-plugins.md

@@ -16,8 +16,7 @@ A minimal plugin should confirm to the following structure:
 ```
 plugin-name
 ├── README.md
-└── src
-    └── init.lua
+└── init.lua
 ```
 
 You can also use
@@ -27,7 +26,7 @@ You can also use
 
 This is where you document what the plugin does, how to use it, etc.
 
-### src/init.lua
+### init.lua
 
 This file is executed to load the plugin. It should expose a `setup()`
 function, which will be used by the users to setup the plugin.