Dev Containers: Add markdownlint extension

.devcontainer/devcontainer.json

@@ -31,6 +31,7 @@
   "customizations": {
     "vscode": {
       "extensions": [
+        "DavidAnson.vscode-markdownlint",
         "eamodio.gitlens@11.7.0",
         "editorconfig.editorconfig",
         "exiasr.hadolint",

.devcontainer/ghc-9.2/devcontainer.json

@@ -32,6 +32,7 @@
       "extensions": [
         "alefragnani.project-manager",
         "christian-kohler.path-intellisense",
+        "DavidAnson.vscode-markdownlint",
         "eamodio.gitlens@11.7.0",
         "editorconfig.editorconfig",
         "exiasr.hadolint",

.devcontainer/ghc-9.4/devcontainer.json

@@ -31,6 +31,7 @@
       "extensions": [
         "alefragnani.project-manager",
         "christian-kohler.path-intellisense",
+        "DavidAnson.vscode-markdownlint",
         "eamodio.gitlens@11.7.0",
         "editorconfig.editorconfig",
         "exiasr.hadolint",

.devcontainer/ghc-9.6/devcontainer.json

@@ -31,6 +31,7 @@
       "extensions": [
         "alefragnani.project-manager",
         "christian-kohler.path-intellisense",
+        "DavidAnson.vscode-markdownlint",
         "eamodio.gitlens@11.7.0",
         "editorconfig.editorconfig",
         "exiasr.hadolint",

.devcontainer/ghc-9.8/devcontainer.json

@@ -31,6 +31,7 @@
       "extensions": [
         "alefragnani.project-manager",
         "christian-kohler.path-intellisense",
+        "DavidAnson.vscode-markdownlint",
         "eamodio.gitlens@11.7.0",
         "editorconfig.editorconfig",
         "exiasr.hadolint",