Tcl. Fix mid-page rendering error

Github's syntax-highlighting has an error in the Tcl syntax-parser causing the rendering of the page to fail about one third in.

This commit bypasses this rendering-error by resetting the syntax highlighting after the error has occurred.

tcl.html.markdown

@@ -149,6 +149,9 @@ set greeting "Hello, [set {first name}]"
 
 # To promote the words within a word to individual words of the current
 # command, use the expansion operator, "{*}".
+```
+
+```tcl
 set {*}{name Neo}
 
 # is equivalent to