While installing meson using pip3 install --user meson, due to python
path issues, build.ninja can't be located by ninja. meson generates
ninja files fine, but then when you run ninja, it is unable to find
meson's build.ninja python module due to path issues.
It gives the following error on ninja -C build install:

ninja: Entering directory `build'
ninja: error: loading 'build.ninja': No such file or directory

After uninstalling meson using pip3 and installing it again using pip
without --user argument solved the issue.

Add a troubleshooting section to the readme to describe this issue and
suggest possible solutions.

Signed-off-by: Vedant Paranjape <vedantparanjape160201@gmail.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>