doc: Add doc to support new snippet engines

lua/neogen/init.lua

@@ -98,7 +98,7 @@ end
 --- <
 ---   Default configurations for a languages can be found in `lua/neogen/configurations/<your_language>.lua`
 ---
----  - To know which snippet engines are supported, take a look at |snippet-integration|.
+---  - To know which snippet engines are supported, take a look at |neogen-snippet-integration|.
 ---    Example: `snippet_engine = "luasnip"`
 ---
 ---@toc_entry Configure the setup
@@ -222,7 +222,7 @@ end
 ---   - Improve godoc template (#75)
 --- ## 2.3.0~
 ---   - Added bundled support with snippet engines !
----     Check out |snippet-integration| for basic setup
+---     Check out |neogen-snippet-integration| for basic setup
 --- ## 2.2.0~
 ---   ### Python~
 ---     - Add support for `*args` and `**kwargs`

lua/neogen/snippet.lua

@@ -10,7 +10,18 @@ local notify = require("neogen.utilities.helpers").notify
 --- <
 --- Some snippet engines come out of the box bundled with neogen:
 --- - `"luasnip"` (https://github.com/L3MON4D3/LuaSnip)
----@tag snippet-integration
+---
+--- # Add support for snippet engines~
+---
+--- To add support to a snippet engine, go to `lua/neogen/snippet.lua`.
+--- There's a table called `snippet.engines` that holds functions that will be called
+--- depending of the snippet engine
+---
+--- Those functions have this signature:
+--- `snippet_engine_name = function (snip, pos)` where
+--- - `snip` is a lsp styled snippet (in table format)
+--- - `pos` is a { row , col } table for placing the snippet
+---@tag neogen-snippet-integration
 ---@toc_entry Use popular snippet engines
 local snippet = {}
 snippet.engines = {}