github: additionally ask for log files on build problems and questions

.github/ISSUE_TEMPLATE/5_feature_request.md

@@ -13,3 +13,10 @@ https://github.com/mpv-player/mpv/labels/meta%3Afeature-request
 ### Expected behavior of the wanted feature
 
 ### Alternative behavior of the wanted feature
+
+### Log file
+
+Even if you think it's not necessary at first, it might help us later to find
+possible issues. Make a log file made with -v -v or --log-file=output.txt, paste
+it to https://0x0.st/ or attach it to the github issue, and replace this text
+with a link to it.

.github/ISSUE_TEMPLATE/6_question.md

@@ -16,3 +16,10 @@ described and needs clarification.
 
 Before asking a question make sure it hasn't been asked or answered yet.
 https://github.com/mpv-player/mpv/labels/meta%3Aquestion
+
+### Log file
+
+Even if you think it's not necessary at first, it might help us later to find
+possible issues. Make a log file made with -v -v or --log-file=output.txt, paste
+it to https://0x0.st/ or attach it to the github issue, and replace this text
+with a link to it.