Introduce FAQ in docs (#2917)

* Introduce  FAQ

Future work:

* Remove much of same info from trouble-shooting section.
* Remove duplicate info from Kivy framework FAQ.
* Link to this from Kivy framework FAQ.

* Apply suggestions from code review

Still to do: Remove obsolete section.

Co-authored-by: Mirko Galimberti <[email protected]>

* Remove obsolete entry

---------

Co-authored-by: Mirko Galimberti <[email protected]>

Author: Julian-O

FAQ.md

@@ -0,0 +1,73 @@
+# FAQ for python-for-android (p4a)
+
+## Introduction
+
+[python-for-android](https://python-for-android.readthedocs.io/) is an open
+source build tool to let you package Python code into standalone Android artifacts (APKs, AABs, AARs).
+These can be passed around, installed, or uploaded to marketplaces such as the
+Play Store just like any other Android app.
+
+### Sibling Projects:
+
+This tool was originally developed for apps produced with
+the [Kivy framework](https://github.com/kivy/kivy), and is
+managed by the same team. However, it can be used to build other types of Python
+apps for Android.
+
+p4a is often used in conjunction
+with [Buildozer](https://github.com/kivy/buildozer), which can download, install
+and keep up-to-date any necessary prerequisites (including p4a itself), for a
+number of target platforms, using a specification file to define the build.
+
+### Is it possible to have a kiosk app on Android?
+
+Thomas Hansen wrote a detailed answer
+on [the kivy-users mailing list](https://groups.google.com/d/msg/kivy-users/QKoCekAR1c0/yV-85Y_iAwoJ)
+
+Basically, you need to root the device, remove the SystemUI package, add some
+lines to the xml configuration, and you're done.
+
+### Common Errors
+
+The following are common problems and resolutions that users have reported.
+
+
+#### AttributeError: ‘Context’ object has no attribute ‘hostpython’
+
+This is a known bug in some releases. To work around it, add your python
+requirement explicitly, e.g. `--requirements=python3,kivy`. This also applies
+when using buildozer, in which case add python3 to your buildozer.spec
+requirements.
+
+#### linkname too long
+
+This can happen when you try to include a very long filename, which doesn’t
+normally happen but can occur accidentally if the p4a directory contains a
+`.buildozer` directory that is not excluded from the build (e.g. if buildozer
+was previously used). Removing this directory should fix the problem, and is
+desirable anyway since you don’t want it in the APK.
+
+#### Requested API target XX is not available, install it with the SDK android tool
+
+This means that your SDK is missing the required platform tools. You need to
+install the `platforms;android-XX` package in your SDK, using the android or
+sdkmanager tools (depending on SDK version).
+
+If using buildozer this should be done automatically, but as a workaround you
+can run these from `~/.buildozer/android/platform/android-sdk-XX/tools/android`
+
+#### SSLError(“Can’t connect to HTTPS URL because the SSL module is not available.”)
+Your hostpython3 was compiled without SSL support. You need to install the SSL
+development files before rebuilding the hostpython3 recipe. Remember to always
+clean the build before rebuilding (`p4a clean builds`, or with buildozer `buildozer
+android clean`).
+
+On Ubuntu and derivatives:
+
+    apt install libssl-dev
+    p4a clean builds # or with: buildozer `buildozer android clean
+
+On macOS:
+
+    brew install openssl
+    p4a clean builds # or with: buildozer `buildozer android clean