Add section about extended wait time to template

And other minor adjustments.

.github/PULL_REQUEST_TEMPLATE.md

 <!--
 Your pull request will be reviewed automatically and by a human.
 
-Please ensure the automated reviews pass. Follow the instructions provided, if necessary.
-You can speed up the process by [running some tests locally](https://packagecontrol.io/docs/submitting_a_package#Step_7).
+The manual review may take several days or weeks, depending on the reviewer's availability and workload.
+If you haven't received a comment on your pull request and it wasn't merged either,
+it just hasn't been reviewed yet.
+
+---
+
+Please ensure the automated reviews pass. 
+Follow the instructions provided, if necessary.
+You can speed up the process
+by [running some tests locally](https://packagecontrol.io/docs/submitting_a_package#Step_7).
 
 In general, make sure you:
 
  1. Used `"tags": true` and not `"branch": "master"` 
-    ([versioning docs](https://packagecontrol.io/docs/submitting_a_package#Step_4))
- 2. Added a readme to your repository so that users (and reviewers) 
+    (versioning docs: <https://packagecontrol.io/docs/submitting_a_package#Step_4>)
+ 2. Added a README to your repository so that users (and reviewers) 
     can understand what your package provides.
  
-You may proceed with a short description of what the package does and, 
-in case a similar package already exists, 
-why you believe it is needed
+You should proceed with a short description of what the package does
+and, in case one or multiple similar package already exists, 
+why you believe it is different and needed
 below this line. -->