Clear executable bits on README.md, Tools.md and tox.ini

They are not executable files.

Change-Id: I65cc69be89e382b8db197ff09a3cf75c7eac4d59
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/README.md b/README.md
old mode 100755
new mode 100644
diff --git a/Tools.md b/Tools.md
old mode 100755
new mode 100644
diff --git a/tox.ini b/tox.ini
old mode 100755
new mode 100644