LSP: install and configure texlab

- Installs and configure texlab which provides LSP and linter for LaTeX.
  Should also allow to build a project, but It is failling right now, I
  don't get why.
- Adds a markdown snippet to get the number of the curret day.
- Adds a markdown snippet to get the current date.
- Improves the syntax of the markdown snippets descriptions.
- Documents the feature of the plugin that provides the snippets search
  through telescope.

Co-Authored-by: iGor milhit <igor@milhit.ch>

init.lua

@@ -195,7 +195,10 @@ require('lazy').setup({
     end,
   },
 
-  { 'benfowler/telescope-luasnip.nvim' },
+  {
+    -- Allow to search for snippets
+    'benfowler/telescope-luasnip.nvim'
+  },
 
   {
     -- Highlight, edit, and navigate code
@@ -486,6 +489,22 @@ local servers = {
       telemetry = { enable = false },
     },
   },
+
+  texlab = {
+    settings = {
+      build = {
+        executable = "tectonic",
+        args = {
+          "-X",
+          "compile",
+          "%f",
+          "--syntex",
+          "--keep-logs",
+          "--keep-intermediates"
+        }
+      }
+    }
+  },
 }
 
 -- Setup neovim lua configuration

my_snippets/markdown.lua

@@ -8,14 +8,21 @@ local fmt = require("luasnip.extras.fmt").fmt
 -- Function to get the datetime
 --   with daylight saving time
 --   according to the locale
-local get_date = function()
+local get_datetime = function()
   return os.date("%Y-%m-%dT%H:%M:%S%z")
 end
 
+-- Function to get the current date
+local get_date = function()
+  return os.date("%Y-%m-%d")
+end
+
+-- Function to get the current month 
 local get_month = function()
   return os.date("%B")
 end
 
+-- Function to get the current year
 local get_month_year = function()
   return os.date("%B-%Y")
 end
@@ -25,27 +32,52 @@ local get_id = function()
   return os.date("%Y%m%d%H%M%S")
 end
 
+-- Function to get the number of the current day 
+local get_day = function()
+  return os.date("%d")
+end
+
 return {
   s(
     {
       trig = "datetime",
       name = "Datetime",
-      dscr = "Insert datetime with locale daylight saving"
+      dscr = "Insert the current datetime with locale daylight saving."
     },
     {
-      f(get_date, {})
+      f(get_datetime, {})
+    }
+  ),
+  s(
+    {
+      trig = "date",
+      name = "Date",
+      dscr = "Insert the current date."
+    },
+    {
+      f(get_datetime, {})
     }
   ),
   s(
     {
       trig = "id",
       Name = "ID",
-      dscr = "Insert an id based on the datetime"
+      dscr = "Insert an id based on the current datetime."
     },
     {
       f(get_id, {})
     }
   ),
+  s(
+    {
+      trig = "today",
+      Name = "Today",
+      dscr = "Insert the number of the current day."
+    },
+    {
+      f(get_day, {})
+    }
+  ),
   s(
     {
       trig = "fm",