Fix 3371 - Add terraform-ls support

doc/ale-supported-languages-and-tools.txt

@@ -486,7 +486,10 @@ Notes:
 * Tcl
   * `nagelfar`!!
 * Terraform
-  * `fmt`
+  * `terraform`
+  * `terraform-fmt-fixer`
+  * `terraform-ls`
+  * `terraform-lsp`
   * `tflint`
 * Texinfo
   * `alex`!!

doc/ale-terraform.txt

@@ -32,6 +32,28 @@ g:ale_terraform_terraform_executable     *g:ale_terraform_terraform_executable*
   This variable can be changed to use a different executable for terraform.
 
 
+===============================================================================
+terraform-ls                                       *ale-terraform-terraform-ls*
+
+Official terraform language server. More stable than *terraform-lsp* but
+currently has less features.
+
+g:ale_terraform_ls_executable                   *g:ale_terraform_ls_executable*
+                                                *b:ale_terraform_ls_executable*
+  Type: |String|
+  Default: `'terraform-ls'`
+
+  This variable can be changed to use a different executable for terraform-ls.
+
+
+g:ale_terraform_ls_options                         *g:ale_terraform_ls_options*
+                                                   *b:ale_terraform_ls_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to pass custom CLI flags to terraform-ls.
+
+
 ===============================================================================
 terraform-lsp                                     *ale-terraform-terraform-lsp*
 

doc/ale.txt

@@ -2984,6 +2984,7 @@ documented in additional help files.
   terraform...............................|ale-terraform-options|
     terraform-fmt-fixer...................|ale-terraform-fmt-fixer|
     terraform.............................|ale-terraform-terraform|
+    terraform-ls..........................|ale-terraform-terraform-ls|
     terraform-lsp.........................|ale-terraform-terraform-lsp|
     tflint................................|ale-terraform-tflint|
   tex.....................................|ale-tex-options|