Revert "Add .txt -> .md symlink"

This reverts commit 13bbff94dea66d838842f8bdbc3e32feea00903f.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/common-trace-format-specification.txt b/common-trace-format-specification.txt
deleted file mode 120000 (symlink)
index e850727..0000000
--- a/common-trace-format-specification.txt
+++ /dev/null
@@ -1 +0,0 @@
-common-trace-format-specification.md
\ No newline at end of file