make tracking core versions easier (#2152)

* nicer commit messasge on updating core

this sets the commit message for updating core module to sth. as
`update deltachat-core-rust submodule to 'prepare 1.68 (#2844)'`
instead of always the same message `update deltachat-core-rust submodule`.

this makes it easier to track changes.

* add a hint to release checklist to include the used core version

docs/release-checklist.md

@@ -15,12 +15,12 @@ this will take some time - meanwhile we're doing some housekeeping:
    $ ./scripts/tx-pull-translations.sh
    $ ./scripts/create-local-help.sh
 
-4. add a device message to ConversationListActivity::onCreate()
-   and update CHANGELOG.md
-   (the core-changelog at
-   https://github.com/deltachat/deltachat-core-rust/blob/master/CHANGELOG.md
-   and the "N commits to master since last release" on
-   https://github.com/deltachat/deltachat-android/releases gives some hints)
+4. a) update CHANGELOG.md
+      from https://github.com/deltachat/deltachat-core-rust/blob/master/CHANGELOG.md
+      and https://github.com/deltachat/deltachat-android/pulls?q=is%3Apr+is%3Aclosed+sort%3Aupdated-desc
+   b) add used core version to CHANGELOG.md
+   c) add a device message to ConversationListActivity::onCreate()
+      or remove the old one
 
 in Android Studio:
 

scripts/update-core.sh

@@ -12,11 +12,12 @@ git submodule update --init --recursive
 cd jni/deltachat-core-rust
 git checkout master
 git pull
+commitmsg=`git log -1 --pretty=%s`
 cd ../..
 
 # commit changes
 git add jni/deltachat-core-rust
-git commit -m "update deltachat-core-rust submodule"
+git commit -m "update deltachat-core-rust submodule to '$commitmsg'"
 
 echo "changes are commited to local repo."
 echo "use 'git push' to use them or 'git reset HEAD~1; git submodule update --recursive' to abort on your own risk :)"