templates: Improve GitHub issue templates.

Author: sundanc

.github/ISSUE_TEMPLATE/01_crash.md

@@ -23,6 +23,9 @@ How can you reproduce the bug?
 
 ```
 
+### Frequency of occurrence
+<!-- Does this happen every time, or only occasionally? -->
+
 ### How are you running the application?
 Please include as many of the following as possible:
 - **Zulip-terminal version:**

.github/ISSUE_TEMPLATE/02_bug.md

@@ -34,3 +34,6 @@ Please include as many of the following as possible:
 If possible, please provide details from the `About` menu: (hotkey: Meta + ?)
 (this can provide some of the details above)
 
+### Logs or additional context
+<!-- Include any logs, screenshots, or other context to help diagnose the issue. -->
+

.github/ISSUE_TEMPLATE/03_parity.md

@@ -20,6 +20,10 @@ If you know:
   (see https://zulip.com/api/changelog)
 
 
+### Impact on user experience
+<!-- How does the absence of this feature affect users? -->
+
+
 ### Other details
 
 

.github/ISSUE_TEMPLATE/04_platform.md

@@ -17,3 +17,6 @@ NOTE: If your proposed feature:
 
 <!-- If discussed in #zulip-terminal or another channel on chat.zulip.org, paste link below: -->
 
+### Potential challenges or limitations
+<!-- Are there any edge cases, constraints, or limitations to consider? -->
+

.github/pull_request_template.md

@@ -8,6 +8,11 @@
 <!-- Do you not understand something? Are you unsure about a certain approach? Want feedback? -->
 - [ ] 
 
+### Documentation updates    <!-- DELETE SECTION IF NOT APPLICABLE -->
+<!-- Does this PR require updates to documentation? -->
+- [ ] Documentation updated
+- [ ] No documentation changes required
+
 ### External discussion & connections
 <!-- [x] all that apply, specifying topic and adding numbers after # for issues/PRs -->
 - [ ] Discussed in **#zulip-terminal** in `topic`