docs(branding): collect ASCII study assets with README

Move the four leftover ASCII variants from the repo root into
HellionChat/images/ascii/ and add a README that explains which two
files are embedded in the plugin DLL versus which ones stay as study
material. The original paw file was split into a stipple version and
an outline version because the two paws were stacked in one source.

Attribution:

- fox-*.txt files are by Julia Moon, drawn for Hellion Chat, free to
  use without attribution
- wolf-head-blazejkozlowski.txt is by Blazej Kozlowski, originally
  published on asciiart.eu, kept as a style reference

HellionChat/images/ascii/wolf-head-blazejkozlowski.txt

@@ -0,0 +1,26 @@
+                              __
+                            .d$$b
+                          .' TO$;\
+                         /  : TP._;
+                        / _.;  :Tb|
+                       /   /   ;j$j
+                   _.-"       d$$$$
+                 .' ..       d$$$$;
+                /  /P'      d$$$$P. |\
+               /   "      .d$$$P' |\^"l
+             .'           `T$P^"""""  :
+         ._.'      _.'                ;
+      `-.-".-'-' ._.       _.-"    .-"
+    `.-" _____  ._              .-"
+   -(.g$$$$$$$b.              .'
+     ""^^T$$$P^)            .(:
+       _/  -"  /.'         /:/;
+    ._.'-'`-'  ")/         /;/;
+ `-.-"..--""   " /         /  ;
+.-" ..--""        -'          :
+..--""--.-"         (\      .-(\
+  ..--""              `-\(\/;`
+    _.                      :
+                            ;`-
+                           :\
+                           ;  bug