Fix bug with pound signs used to mark sections.

Also update tests/scribble/markdown-docs files accordingly.

original commit: faeba879e292414dd6d5d9e38d4a08b26e63cceb

collects/scribble/markdown-render.rkt

@@ -39,8 +39,9 @@
 
     (define/override (render-part d ht)
       (let ([number (collected-info-number (part-collected-info d ht))])
-        (printf (make-string (add1 (length number)) #\#))
-        (printf " ")
+        (unless (zero? (length number))
+          (printf (make-string (length number) #\#))
+          (printf " "))
         (for ([n (in-list (reverse number))] #:when n) (printf "~s." n))
         (when (part-title-content d)
           (when (ormap values number) (printf " "))

collects/tests/scribble/markdown-docs/example.md

@@ -1,12 +1,22 @@
-# ```scheme
- (require racket/string)
-```
+# 1. Section
+
+This is a top-level section.
+
+## 1.1. Subsection
+
+This is a subsection.
+
+### 1.1.1. Subsubsection
+
+This is a subsubsection.
+
+Here is an itemize:
 
 * Item 1.
 
 * Item 2.
 
-## 1. Section
+Here is a hyperlink:
 
 [I am a hyperlink to Racket.](http://www.racket-lang.org/)
 
@@ -16,12 +26,14 @@ _Italic_. \_Just underlines\_.
 
 “Dobule quoted”. ‘Single quoted’.
 
+Example of vebatim:
+
 `Hi, world.`  
 `A “quote”.`  
 `Second line.`
 `Last line.`  
 
-The end.
+Another example of verbatim, with ticks/quotes:
 
 `THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS`   
 `“AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT`     
@@ -35,6 +47,14 @@ The end.
 `(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE` 
 `OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.`  
 
+Example of a defmodule:
+
+```scheme
+ (require racket/string)
+```
+
+Example of a defproc:
+
 ```scheme
 (make-string k [char]) -> string?
   k : exact-nonnegative-integer? 

collects/tests/scribble/markdown-docs/example.scrbl

@@ -3,14 +3,26 @@
 @(require scribble/manual
           (for-label racket/base racket/contract racket/string))
 
-@defmodule[racket/string]
+@section{Section}
+
+This is a top-level section.
+
+@subsection{Subsection}
+
+This is a subsection.
+
+@subsubsection{Subsubsection}
+
+This is a subsubsection.
+
+Here is an itemize:
 
 @itemize[
 @item{Item 1.}
 @item{Item 2.}
 ]
 
-@section{Section}
+Here is a hyperlink:
 
 @hyperlink["http://www.racket-lang.org/" "I am a hyperlink to Racket."]
 
@@ -23,6 +35,8 @@ _Just underlines_.
 ``Dobule quoted''.
 `Single quoted'.
 
+Example of vebatim:
+
 @verbatim{
 Hi, world.
 A ``quote''.
@@ -30,7 +44,7 @@ Second line.
 Last line.
 }
 
-The end.
+Another example of verbatim, with ticks/quotes:
 
 @verbatim{
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
@@ -46,6 +60,12 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 }
 
+Example of a defmodule:
+
+@defmodule[racket/string]
+
+Example of a defproc:
+
 @defproc[(make-string [k exact-nonnegative-integer?][char char? #\nul]) string?]{
 
 Returns a new mutable string of length @racket[k] where each position in the