Update variables.html (#222)

Always mention $HOME , not just most of the time.

lib/init/variables.html

@@ -53,7 +53,7 @@ into GRASS, store them in:<br>
 <h2>Setting GRASS gisenv variables</h2>
 
 Use <em><a href="g.gisenv.html">g.gisenv</a></em> within GRASS. This permanently
-predefines GRASS variables in the <tt>.grass7/rc</tt> file.
+predefines GRASS variables in the <tt>$HOME/.grass7/rc</tt> file.
 <br><br>
 Usage:
 <div class="code"><pre>
@@ -82,7 +82,7 @@ PERMANENT
     startup script.</dd>
   
   <dt>GISRC</dt>
-  <dd>name of <tt>.grass7/rc</tt> file. Defines the system wide value
+  <dd>name of <tt>$HOME/.grass7/rc</tt> file. Defines the system wide value
     while in a GRASS session.</dd>
   
   <dt>GRASS_ADDON_PATH</dt>