Merge branch 'jk/doc-backslash-in-exclude' into next

The patterns used in the .gitignore files use backslash in the way
documented for fnmatch(3); document as such to reduce confusion.

* jk/doc-backslash-in-exclude:
  doc: document backslash in gitignore patterns

Author: gitster

Documentation/gitignore.adoc

@@ -111,6 +111,11 @@ PATTERN FORMAT
    one of the characters in a range. See fnmatch(3) and the
    FNM_PATHNAME flag for a more detailed description.
 
+ - A backslash ("`\`") can be used to escape any character. E.g., "`\*`"
+   matches a literal asterisk (and "`\a`" matches "`a`", even though
+   there is no need for escaping there). As with fnmatch(3), a backslash
+   at the end of a pattern is an invalid pattern that never matches.
+
 Two consecutive asterisks ("`**`") in patterns matched against
 full pathname may have special meaning:
 

t/t3070-wildmatch.sh

@@ -235,6 +235,8 @@ match 1 1 1 1 aaaaaaabababab '*ab'
 match 1 1 1 1 'foo*' 'foo\*'
 match 0 0 0 0 foobar 'foo\*bar'
 match 1 1 1 1 'f\oo' 'f\\oo'
+match 0 0 0 0 \
+      1 1 1 1 'foo\' 'foo\'
 match 1 1 1 1 ball '*[al]?'
 match 0 0 0 0 ten '[ten]'
 match 1 1 1 1 ten '**[!te]'