ELF: Fix man page formatting.

Author: pcc

lld/docs/ld.lld.1

@@ -91,7 +91,7 @@ Bind default visibility defined function symbols locally for
 .It Fl Bsymbolic-non-weak-functions
 Bind default visibility defined STB_GLOBAL function symbols locally for
 .Fl shared.
-.It Fl --be8
+.It Fl -be8
 Write a Big Endian ELF File using BE8 format(AArch32 only)
 .It Fl -build-id Ns = Ns Ar value
 Generate a build ID note.