docs/ide-support.md: Update instructions for clangd
docs/ide-support.md: Update instructions for clangd

The native Makefiles can now generate a compile_commands.json for
clangd.
Update and simplify instructions by removing the dependencies on bear
and the Python script that translates the paths outside the chroot.

BUG=b:236389226,b:176500425
TEST=none
BRANCH=none

Cq-Depend: chromium:3826375
Signed-off-by: Andrea Grandi <f017805e76e0e7a74072a3bac1b6e29e65eedeab@google.com>
Change-Id: I2f2f654c175e3ad5e076c621b02a7ec28cea88f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3859872
Reviewed-by: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>
Reviewed-by: Bobby Casey <a3c107f0b4efaee07148ab0813ba992bba562a69@google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec