Created Obtain logs for debug (markdown)

Obtain-logs-for-debug.md

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+Prerequisites: Android SDK is installed on your computer. Specifically, `adb` is available.
+
+On command line:
+1. Find out the process ID (`PID`) of AntennaPod. e.g., using `ps` . It is 21638 in the following example
+```shell
+# In a terminal on your computer with Android SDK
+$ adb shell
+perry_f:/ $ ps | grep de.danoeh.antennapod
+u0_a432   23771 681   992528 32408 SyS_epoll_ 00000000 S de.danoeh.antennapod
+perry_f:/ $ exit
+```
+
+2. Use `adb logcat` to dump the output to a file, e.g.
+```
+$ adb logcat --pid=23771 -d > logcat.log
+```
+
+Notes:
+- See [Logcat documentation](https://developer.android.com/studio/command-line/logcat) for tweaking the outputs. Some useful ones include: 
+    - `-t '<time>'` : show logs only since the specified time (to reduce output)
+    - `-e <expr>` : filter output by regular expression
+- sometimes you might all the logs. (no `--pid` argument), as some fatal error will cause Android runtime to indicate errors in the log (that might be helpful) that are out of AntennaPod's process.