METRON-2330: Add global profile in foreach desc

I had a hard time figuring out the reason behind using exactly 'global'.

site/current-book/metron-analytics/metron-profiler-common/index.html

@@ -289,7 +289,16 @@ <h4><a name="profile"></a><tt>profile</tt></h4>
 <h4><a name="foreach"></a><tt>foreach</tt></h4>
 <p><i>Required</i></p>
 <p>A separate profile is maintained &#x2018;for each&#x2019; of these.  This is effectively the entity that the profile is describing.  The field is expected to contain a Stellar expression whose result is the entity name.</p>
-<p>For example, if <tt>ip_src_addr</tt> then a separate profile would be maintained for each unique IP source address in the data; 10.0.0.1, 10.0.0.2, etc.</p></div>
+<p>For example, if <tt>ip_src_addr</tt> then a separate profile would be maintained for each unique IP source address in the data; 10.0.0.1, 10.0.0.2, etc.</p>
+<p>Also, global profile can be declared using Stellar expression that returns a string:</p></div>
+
+<div>
+<div>
+<pre class="source">&quot;foreach&quot;: &quot;&#x2018;global&quot;&#x2019;
+</pre></div></div>
+
+ <p>Any other string can be used instead of global.</p>Any other string can be used instead of global.Any other string can be used instead of global.
+
 <div class="section">
 <h4><a name="onlyif"></a><tt>onlyif</tt></h4>
 <p><i>Optional</i></p>