docs: Edit upload-and-share-files.md to conform to style guide.

templates/zerver/help/upload-and-share-files.md

@@ -2,42 +2,35 @@
 
 Zulip allows you to easily attach files, including images, sound, and video by:
 
-- *Clicking the Paperclip Icon* Use the paperclip icon
-  (<i class="icon-vector-paper-clip"></i>) located under the
-  message field.
-- *Dragging* You may also drag and drop files on the message
+- **Clicking the Paperclip Icon** - Use the paperclip icon
+  (![paperclip](/static/images/help/paperclip.png)) located under the message field.
+- **Dragging and dropping** - You may also drag and drop files on the message
   field. The files are uploaded to a server and a link is supplied,
-  but a thumbnail is displayed if possible. The link to the file will
-  be in Markdown format: `[link_text](link_URL)`
+  but a thumbnail is displayed if possible. The link to the file will be
+  in Markdown format: `[link_text](link_URL)`
 
-![before](/static/images/help/file_upload_before.png)
-
-If you wish to give your image a caption or title, you may add text
-before or after the generated link. Any text you add in the box will
-not break the link to your file so long as the file link remains
-intact.
-
----
+!!! tip ""
+    If you wish to give your image a caption or title, you may add text before
+    or after the generated link in your message.
 
 After submitting your message, you will see a clickable thumbnail if
 your file is a common image type (i.e. PNG, JPEG, etc.). All other
 files will simply have a link displayed.
 
-![after](/static/images/help/file_upload_after_image_preview.png)
-
 ### Link Behavior
 
-Clicking all file links will open a new tab that will
-either 1. display the file if it is an image or 2. download the file
-automatically to your computer.
+Clicking all file links will open a new tab that will either:
+- display the file if it is an image.
+- download the file automatically to your computer.
 
-If the file has a thumbnail, clicking it will open a lightbox modal
-with varying options depending on the media type. Images may be opened
-in new tabs or downloaded, while videos from Youtube may only be
-opened (and not downloaded). You can exit out of a lightbox by
-clicking the space around the media preview or by clicking the exit
-button found in the upper right-hand corner.
+If the file has a thumbnail, clicking it will open a lightbox modal with
+varying options depending on the media type. Images may be opened in new tabs or
+downloaded, while videos from Youtube may only be opened (and not downloaded).
 
+!!! tip ""
+    You can exit out of a lightbox by clicking the space around the media preview
+    or by clicking the exit button (![x](/static/images/help/x.png)) found in
+    the upper right-hand corner.
 
 ### Sharing Files from External Websites
 
@@ -45,5 +38,3 @@ Images and videos shared from external websites, such as Imgur or
 Youtube, may have previews generated as well. Clicking previews of
 images/videos from external websites will lead to the same lightbox
 behavior described above.
-
-![external](/static/images/help/file_share_imgur_preview.png)