fix(doc): update README.md and file resource documentation (#659)

Signed-off-by: Pavel Boldyrev <627562+bpg@users.noreply.github.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -20,6 +20,6 @@ Please add screenshots, logs, or other relevant information that demonstrates th
 <!--- Thank you for keeping this note for the community --->
 
 <!--- If your PR fully resolves and should automatically close the linked issue, use Closes. Otherwise, use Relates --->
-Relates OR Closes #0000
+Closes #0000 | Relates #0000
 
 <!--- Release note for [CHANGELOG](https://github.com/bpg/terraform-provider-proxmox/blob/main/CHANGELOG.md) will be created automatically using the PR's title, update it accordingly. --->

README.md

@@ -1,4 +1,5 @@
 # Terraform Provider for Proxmox
+
 [![Go Report Card](https://goreportcard.com/badge/github.com/bpg/terraform-provider-proxmox)](https://goreportcard.com/report/github.com/bpg/terraform-provider-proxmox)
 [![GoDoc](https://godoc.org/github.com/bpg/terraform-provider-proxmox?status.svg)](http://godoc.org/github.com/bpg/terraform-provider-proxmox)
 [![GitHub release (latest by date)](https://img.shields.io/github/v/release/bpg/terraform-provider-proxmox)](https://github.com/bpg/terraform-provider-proxmox/releases/latest)
@@ -25,7 +26,9 @@ backwards compatibility between provider versions as much as possible.
 
 ## Requirements
 
-- [Terraform](https://www.terraform.io/downloads.html) 1.2+
+- [Proxmox Virtual Environment](https://www.proxmox.com/en/proxmox-virtual-environment/) 8.x
+- TLS 1.3 for the Proxmox API endpoint
+- [Terraform](https://www.terraform.io/downloads.html) 1.4+
 - [Go](https://golang.org/doc/install) 1.21 (to build the provider plugin)
 
 ## Building the provider
@@ -61,11 +64,17 @@ make test
 
 Tests are limited to regression tests, ensuring backwards compatibility.
 
+A limited number of acceptance tests are available in the `proxmoxtf/test` directory, mostly
+for "new" functionality implemented using the Terraform Provider Framework. These tests
+are not run by default, as they require a Proxmox VE environment to be available.
+They can be run using `make testacc`, the Proxmox connection can be configured using
+environment variables, see provider documentation for details.
+
 ## Deploying the example resources
 
-There are number of TF examples in the `examples` directory, which can be used
+There are number of TF examples in the `example` directory, which can be used
 to deploy a Container, VM, or other Proxmox resources on your test Proxmox
-cluster. The following assumptions are made about the test Proxmox cluster:
+environment. The following assumptions are made about the test environment:
 
 - It has one node named `pve`
 - The node has local storages named `local` and `local-lvm`
@@ -237,6 +246,7 @@ using SFTP. This requires the use of a PAM account (standard Linux account).
 ## Sponsorship
 
 ❤️ This project is sponsored by:
+
 - [TJ Zimmerman](https://github.com/zimmertr)
 
 Thanks again for your support, it is much appreciated! 🙏

docs/resources/virtual_environment_file.md

@@ -58,19 +58,23 @@ EOF
 
 ## Argument Reference
 
-- `content_type` - (Optional) The content type.
-    - `backup`
-    - `iso`
-    - `snippets`
-    - `vztmpl`
+- `content_type` - (Optional) The content type. If not specified, the content type will be inferred from the file
+  extension. Valid values are:
+    - `backup` (allowed extensions: `.vzdump`)
+    - `iso` (allowed extensions: `.iso`, `.img`)
+    - `snippets` (allowed extensions: any)
+    - `vztmpl` (allowed extensions: `.tar.gz`, `.tar.xz`, `tar.zst`)
 - `datastore_id` - (Required) The datastore id.
 - `node_name` - (Required) The node name.
 - `overwrite` - (Optional) Whether to overwrite an existing file (defaults to
   `true`).
-- `source_file` - (Optional) The source file (conflicts with `source_raw`).
+- `source_file` - (Optional) The source file (conflicts with `source_raw`), could be a
+  local file or a URL. If the source file is a URL, the file will be downloaded
+  and stored locally before uploading it to Proxmox VE.
     - `checksum` - (Optional) The SHA256 checksum of the source file.
     - `file_name` - (Optional) The file name to use instead of the source file
-      name.
+      name. Useful when the source file does not have a valid file extension, for example 
+      when the source file is a URL referencing a `.qcow2` image.
     - `insecure` - (Optional) Whether to skip the TLS verification step for
       HTTPS sources (defaults to `false`).
     - `path` - (Required) A path to a local file or a URL.
@@ -103,13 +107,17 @@ unconditionally replace it and take ownership of the resource. On destruction,
 the file will be deleted as if it did not exist before. If you want to prevent
 the resource from replacing the file, set `overwrite` to `false`.
 
+Make sure the target datastore supports the content type you are uploading. For
+example, the `snippets` content type can be disabled by default on the `local`
+datastore.
+
 ## Import
 
 Instances can be imported using the `node_name`, `datastore_id`, `content_type`
 and the `file_name` in the following format:
 
-```
-<node_name>:<datastore_id>/<content_type>/<file_name>
+```text
+node_name:datastore_id/content_type/file_name
 ```
 
 Example: