[PATCH] gitignore.txt: suggestions how to get literal # or ! at the beginning

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

We support backslash escape, but we hide the details behind the phrase
"a shell glob suitable for consumption by fnmatch(3)". So it may not
be obvious how one can get literal # or ! at the beginning of a pattern.
Add a few lines on how to work around the magic characters.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Asciidoc 8.2.6 does not like me writing
 "Put \# if you need a literal #.." so I go with "backslash" and
 "hash" instead. `\!` displays fine both in man page and html format.
 '!' changed to `!` because it looks clearer in monospace.

 Documentation/gitignore.txt | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Documentation/gitignore.txt b/Documentation/gitignore.txt
index 96639e0..8c03ed4 100644
--- a/Documentation/gitignore.txt
+++ b/Documentation/gitignore.txt
@@ -74,11 +74,14 @@ PATTERN FORMAT
    for readability.
 
  - A line starting with # serves as a comment.
+   Put a backslash in front of the first hash for the patterns
+   that start with a hash.
 
- - An optional prefix '!' which negates the pattern; any
+ - An optional prefix `!` which negates the pattern; any
    matching file excluded by a previous pattern will become
    included again.  If a negated pattern matches, this will
-   override lower precedence patterns sources.
+   override lower precedence patterns sources. Use `\!` if
+   you need a literal `!` at the beginning of the pattern.
 
  - If the pattern ends with a slash, it is removed for the
    purpose of the following description, but it would only find
-- 
1.7.12.1.406.g6ab07c4