feat(gdscript): improve descriptions

/spend 1h

Author: Goutte

modules/openapi-generator/src/main/resources/gdscript/api_doc_example.handlebars

@@ -25,8 +25,9 @@ var {{paramName}} = {{dataType}}.new()
 api.{{{operationIdSnakeCase}}}(
 {{#each allParams}}
 	# {{paramName}}{{#if dataType}}: {{dataType}}{{/if}}{{#if defaultValue}} = {{{defaultValue}}}{{/if}}{{#if example}}   Eg: {{{example}}}{{/if}}
-	# {{{description}}}
-	{{! `example` is not available here, not sure why }}
+    {{~#if description}}
+
+	# {{{description}}}{{/if}}
 	{{paramName}},
 {{/each}}
 	# On Success

modules/openapi-generator/src/main/resources/gdscript/partials/api_method_params.handlebars

@@ -1,6 +1,8 @@
 	{{#each allParams}}
 	# {{paramName}}{{#if dataType}}: {{dataType}}{{/if}}{{#if defaultValue}} = {{{defaultValue}}}{{/if}}{{#if example}}   Eg: {{{example}}}{{/if}}
-	# {{{description}}}
+    {{~#if description}}
+
+	# {{{description}}}{{/if}}
 	{{paramName}}{{#if required}}{{#if dataType}}: {{{dataType}}}{{/if}}{{/if}}{{#unless required}} = {{#if defaultValue}}{{{defaultValue}}}{{/if}}{{#unless defaultValue}}null{{/unless}}{{/unless}},
 	{{/each}}
 	on_success: Callable = Callable(),  # func(response: {{>partials/api_response_class_name}})

samples/client/petstore/gdscript/addons/oas.petstore.client/apis/DemoPetApi.gd

@@ -95,7 +95,6 @@ func delete_pet(
 	# Pet id to delete
 	petId: float,
 	# apiKey: String = ""   Eg: apiKey_example
-	# 
 	apiKey = "",
 	on_success: Callable = Callable(),  # func(response: DemoApiResponse)
 	on_failure: Callable = Callable(),  # func(error: DemoApiError)
@@ -133,7 +132,6 @@ func delete_pet_threaded(
 	# Pet id to delete
 	petId: float,
 	# apiKey: String = ""   Eg: apiKey_example
-	# 
 	apiKey = "",
 	on_success: Callable = Callable(),  # func(response: DemoApiResponse)
 	on_failure: Callable = Callable(),  # func(error: DemoApiError)

samples/client/petstore/gdscript/addons/oas.petstore.client/apis/DemoPetApi.md

@@ -98,7 +98,6 @@ api.delete_pet(
 	# Pet id to delete
 	petId,
 	# apiKey: String = ""   Eg: apiKey_example
-	# 
 	apiKey,
 	# On Success
 	func(response):