Fix broken command-list.h generation with core.autocrlf

The script generate-cmdlist.sh needs input text files in UNIX line ending to work correctly. It's been fine even with core.autocrlf set because Documentation/git-*.txt is forced LF conversion.

But this leaves out gitk.txt and also Documentation/*config.txt that recently becomes new input for this script. Update the attribute file to force LF on all *.txt files to be on the safe side.

For more details, please see 00ddc9d13c (Fix build with core.autocrlf=true - 2017-05-09)

---
Some tests must have broken out of the test repo and set core.autocrlf on my $GIT_DIR/config. Fun was not had.

 .gitattributes | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 49b3051641..acf853e029 100644
@@ -5,7 +5,7 @@
 *.pl eof=lf diff=perl
 *.pm eol=lf diff=perl
 *.py eol=lf diff=python
-/Documentation/git-*.txt eol=lf
+/Documentation/**/*.txt eol=lf
 /command-list.txt eol=lf
 /GIT-VERSION-GEN eol=lf
 /mergetools/* eol=lf

2.19.1.1231.g84aef82467