Rename :docs-link etc to :docs_link

This appears to fix the error in [issue
3577](emacs-lsp#3577) for me: as I
made these edits in my local straight copy of lsp-mode, I saw the error
message (which was appearing when I called 'revert-buffer in a
non-terraform buffer for which lsp-mode was configured) move from
reporting

```
Error running timer: (error "Eager macro-expansion failure: (error
\"Unknown key: :docs-link.  Available keys: (:name :docs_link :version
:source_type :dependent_modules)\")")
```

to

```
Error running timer: (error "Eager macro-expansion failure: (error
\"Unknown key: :source-type.  Available keys: (:name :docs_link :version
:source_type :dependent_modules)\")")
```

and so on.

Interestingly, flycheck is reporting the exact opposite message now,
claiming that “:docs_link” is an unknown key and “:docs-link” should be
available.

Not sure what’s going on!

clients/lsp-terraform.el

@@ -302,25 +302,25 @@ This is a synchronous action."
                    :installed-version installed-version
                    :version-constraint (lsp-get provider :version_constraint)))
 
-(lsp-defun construct-tf-module ((&terraform-ls:Module :name :docs-link :version :source-type :dependent-modules))
+(lsp-defun construct-tf-module ((&terraform-ls:Module :name :docs_link :version :source_type :dependent_modules))
   "Construct `TF-MODULE' using MODULE."
   (make-tf-module :name name
-                  :doc-link docs-link
+                  :doc-link docs_link
                   :version version
-                  :source-type source-type
-                  :dependent-modules dependent-modules))
+                  :source-type source_type
+                  :dependent-modules dependent_modules))
 
-(lsp-defun lsp-terraform-ls--providers-to-tf-package ((&terraform-ls:Providers :provider-requirements :installed-providers))
+(lsp-defun lsp-terraform-ls--providers-to-tf-package ((&terraform-ls:Providers :provider_requirements :installed_providers))
   "Convert PROVIDERS-TREE-DATA to list of `tf-package'."
-  (let* ((provider-requirements-keys (hash-table-keys provider-requirements))
-         (installed-versions (mapcar (lambda (x) (lsp-get installed-providers (make-symbol (format ":%s" x)))) provider-requirements-keys))
-         (providers (mapcar (lambda (x) (lsp-get provider-requirements (make-symbol (format ":%s" x)))) provider-requirements-keys))
+  (let* ((provider-requirements-keys (hash-table-keys provider_requirements))
+         (installed-versions (mapcar (lambda (x) (lsp-get installed_providers (make-symbol (format ":%s" x)))) provider_requirements-keys))
+         (providers (mapcar (lambda (x) (lsp-get provider_requirements (make-symbol (format ":%s" x)))) provider_requirements-keys))
          (tf-packages (-zip-with (lambda (x y) (construct-tf-package x y)) providers installed-versions)))
     tf-packages))
 
-(lsp-defun lsp-terraform-ls--modules-to-tf-module ((&terraform-ls:ModuleCalls :module-calls))
+(lsp-defun lsp-terraform-ls--modules-to-tf-module ((&terraform-ls:ModuleCalls :module_calls))
   "Convert MODULES-TREE-DATA to list of `TF-MODULE'."
-  (let* ((modules (-map (lambda (x) (construct-tf-module x)) module-calls)))
+  (let* ((modules (-map (lambda (x) (construct-tf-module x)) module_calls)))
     modules))
 
 (defun lsp-terraform-ls--fetch-modules-data (project-root)