docs: added templates for issues and PRs

.github/ISSUE_TEMPLATE

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+**Actual Behaviour**
+
+Please state here what is currently happening.
+
+**Expected Behaviour**
+
+State here what the feature should enable the user to do.
+
+**Steps to reproduce it**
+
+Add steps to reproduce bugs or add information on the place where the feature should be implemented. Add links to a sample deployment or code.
+
+**LogCat for the issue**
+
+Provide logs for the crash here
+
+**Screenshots of the issue**
+
+Where-ever possible add a screenshot of the issue.
+
+**Would you like to work on the issue?**
+
+Let us know if this issue should be assigned to you or tell us who you think could help to solve this issue.

.github/PULL_REQUEST_TEMPLATE

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+Fixes #[Add issue number here. Note: This will automatically closes the issue. If you do not solve the issue entirely, please change the message to e.g. "First steps for issues #IssueNumber]
+
+**Changes**: [Add here what changes were made in this issue and if possible provide links.]
+
+**Screenshot/s for the changes**: [Add screenshot/s of the layout where you made changes or a `*.gif` containing a demonstration]
+
+**Checklist**: [Please tick following check boxes with `[x]` if the respective task is completed]
+- [ ] I have used resources from `strings.xml`, `dimens.xml` and `colors.xml` without hard-coding them
+- [ ] No modifications done at the end of resource files `strings.xml`, `dimens.xml` or `colors.xml`
+- [ ] I have reformatted code in every file included in this PR [<kbd>CTRL</kbd>+<kbd>ALT</kbd>+<kbd>L</kbd>]
+- [ ] My code does not contain any extra lines or extra spaces
+- [ ] I have requested reviews from other members
+
+**APK for testing**: [Compress the `app-debug.apk` file into a `<feature>.rar` or `<feature>.zip` file and upload it here]