Some cosmetic changes

README.md

@@ -31,6 +31,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/db646376a4014c3788c7224e670fe451)](https://app.codacy.com/manual/hosseinmoein/DataFrame?utm_source=github.com&utm_medium=referral&utm_content=hosseinmoein/DataFrame&utm_campaign=Badge_Grade_Dashboard)
 [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/hosseinmoein/DataFrame/master)
 [![Maintenance](https://img.shields.io/badge/Maintained%3F-yes-green.svg)](https://GitHub.com/hosseinmoein/DataFrame/graphs/commit-activity)
+![Conan Center](https://img.shields.io/conan/v/dataframe)
 
 <img src="docs/LionLookingUp.jpg" alt="DataFrame Lion" width="400" longdesc="https://htmlpreview.github.io/?https://github.com/hosseinmoein/DataFrame/blob/master/docs/HTML/DataFrame.html"/>
 

docs/HTML/any_type.html

@@ -47,7 +47,7 @@
   <BR>
 
   <img src="https://github.com/hosseinmoein/DataFrame/blob/master/docs/LionLookingUp.jpg?raw=true" alt="C++ DataFrame"
-       width="200" height="150" style="float:right"/>
+       width="200" height="200" style="float:right"/>
 
 </body>
 </html>

docs/HTML/garbage_in_garbage_out.html

@@ -53,7 +53,7 @@
   <BR>
 
   <img src="https://github.com/hosseinmoein/DataFrame/blob/master/docs/LionLookingUp.jpg?raw=true" alt="C++ DataFrame"
-       width="200" height="150" style="float:right"/>
+       width="200" height="200" style="float:right"/>
 
 </body>
 </html>

docs/HTML/how_to_write_visitors.html

@@ -58,7 +58,8 @@
           <UL>
             <LI><I>void pre()</I>: This is called by DataFrame before passing data to your visitor. You can initialize the process here. And/or reset the process here for repeated use of the same visitor instance.</LI>
             <LI><I>void post()</I>: This is called by DataFrame after it finishes with passing data to your visitor. You can finalize the process here.</LI>
-            <LI><I>result_type &amp;get_result() const</I>: This returns the result of your algorithm. If you have multiple results, define this for the first/main result.</LI>
+            <LI><I>const result_type &amp;get_result() const</I>: This returns the result of your algorithm. If you have multiple results, define this for the first/main result.</LI>
+            <LI><I>result_type &amp;get_result()</I>: non-const version of above, if applicable.</LI>
           </UL>
       </UL>
     <LI>Your visitor will be used by DataFrame's <I>visit()</I> or <I>signle_act_visit()</I> methods.</LI>