doc/installation.txt: replace tabs, remove trailing spaces

Author: ThomasAH

doc/installation.txt

@@ -115,7 +115,7 @@ jinja2
 pyjwt
   To use jwt tokens for login (experimental), install pyjwt. If you
   don't have it installed, jwt tokens are not supported.
-  
+
 Windows Service
   You can run Roundup as a Windows service if pywin32_ is installed.
   Otherwise it must be started manually.
@@ -558,10 +558,10 @@ method.
    installed apache packages, you can use ``dpkg -l | grep apache``.
    If apache2 or apache2-dev are not installed, they install them
    with:
-   
+
    - ``sudo apt update``
    - ``sudo apt install apache2 apache2-dev``
-   
+
 2. If ``pip`` is not already installed, install it with
    ``sudo apt install python-pip``
 
@@ -633,7 +633,7 @@ to configure a UNIX group with appropriate privileges as described in
    ``sudo usermod -a -G mytrackergrp admin``
 3. Add user that runs Apache (the default on Ubuntu is www-data) run:
    ``sudo usermod -a -G mytrackergrp www-data``
-4. Add user mail service runs as (e.g. daemon) run: 
+4. Add user mail service runs as (e.g. daemon) run:
    ``sudo usermod -a -G mytrackergrp daemon``
 5. Change group of the database in the tracker folder run:
    ``sudo chgrp -R mytrackergrp ~/trackers/mytracker``.
@@ -832,23 +832,23 @@ as needed):
     <VirtualHost *:80>
             CustomLog /var/log/apache2/access.log vhost_combined
 
-	    # allow access to roundup docs
+            # allow access to roundup docs
             Alias /doc/ /home/roundup/install/share/doc/roundup/html/
 
-	    # make apache serve static assets like css rather than
+            # make apache serve static assets like css rather than
             # having roundup serve the files
             Alias /foo/@@file/ /srv/roundup/foo/html/
 
-	    # make /foo into /foo/
+            # make /foo into /foo/
             RedirectMatch permanent ^/(foo)$ /$1/
 
-	    # start a wsgi daemon process running as user roundup-foo
-	    # in group roundup-foo. This also changes directory to 
-	    # ~roundup-foo before it starts roundup.wsgi.
+            # start a wsgi daemon process running as user roundup-foo
+            # in group roundup-foo. This also changes directory to
+            # ~roundup-foo before it starts roundup.wsgi.
             WSGIDaemonProcess roundup-foo display-name=roundup-foo user=roundup-foo group=roundup-foo threads=25
 
             # make tracker available at /foo and tie it into the
-	    # wsgi script below.
+            # wsgi script below.
             WSGIScriptAlias /foo /srv/roundup/foo/roundup.wsgi
             <Location /foo>
                     WSGIProcessGroup roundup-foo
@@ -874,12 +874,12 @@ WSGI handler.  This is an enhanced version to be put into
 
     if enabled:
         # Add the directory with the roundup installation
-	# subdirectory to the python path.
+        # subdirectory to the python path.
         sys.path.insert(0, '/home/roundup/install/lib/python')
 
         # obtain the WSGI request dispatcher
         from roundup.cgi.wsgi_handler import RequestDispatcher
-	
+
         tracker_home = os.path.join(os.getcwd(), 'instance')
         application = RequestDispatcher(tracker_home)
     else: