Update issue templates

Author: PhantomShift

.github/ISSUE_TEMPLATE/failing-conversion.md

@@ -0,0 +1,25 @@
+---
+name: Failing Conversion
+about: Report a Source Present in Tachiyomi/Mihon and Kotatsu that Fails to Convert
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+- [ ] I have checked that the source is implemented in the [Kotatsu parsers repo](https://github.com/KotatsuApp/kotatsu-parsers)
+- [ ] I have tried force updating the sources (`nekotatsu update --force-download`)
+- [ ] (OPTIONAL) The source is listed by [Keiyoushi](https://keiyoushi.github.io/extensions/)
+
+**Source Name**
+Name of the source
+
+**Kotatsu Link**
+Link to the file where the parser is implemented
+(e.g. https://github.com/KotatsuApp/kotatsu-parsers/blob/master/src/main/kotlin/org/koitharu/kotatsu/parsers/site/all/MangaDexParser.kt)
+
+**(Optional) Extension Implementation**
+If source has a parser implementation in [Kotatsu](https://github.com/keiyoushi/extensions) and the extension is not included in the [Keiyoushi repo](https://github.com/keiyoushi/extensions) but exists, please provide a link to it.
+
+**Additional context**
+Add any other context about the problem here.