Get rid of references to the master branch

There were some links to the master branch left-over in documentation,
which are now inaccurate after the branch rename. The selftest
definition also references a branch name, so selftests were not running.

Signed-off-by: Toke Høiland-Jørgensen <[email protected]>

.github/workflows/selftests.yml

@@ -2,9 +2,9 @@ name: Selftests
 
 on:
   push:
-    branches: [ master ]
+    branches: [ main ]
   pull_request:
-    branches: [ master ]
+    branches: [ main ]
 
 jobs:
   selftest:

lib/libxdp/README.org

@@ -319,7 +319,7 @@ from some form of control process that has the necessary privileges. The
 xsk_socket__create executed on the non-privileged process will then skip these
 two steps. For an example on how to use these, please take a look at the
 AF_XDP-example program in the bpf-examples repository:
-https://github.com/xdp-project/bpf-examples/tree/master/AF_XDP-example.
+https://github.com/xdp-project/bpf-examples/tree/main/AF_XDP-example.
 
 #+begin_src C
 int xsk_setup_xdp_prog(int ifindex, int *xsks_map_fd);

lib/libxdp/libxdp.3

@@ -361,7 +361,7 @@ from some form of control process that has the necessary privileges. The
 xsk_socket__create executed on the non-privileged process will then skip these
 two steps. For an example on how to use these, please take a look at the
 AF_XDP-example program in the bpf-examples repository:
-\fIhttps://github.com/xdp-project/bpf-examples/tree/master/AF_XDP-example\fP.
+\fIhttps://github.com/xdp-project/bpf-examples/tree/main/AF_XDP-example\fP.
 
 .RS
 .nf

lib/libxdp/protocol.org

@@ -23,7 +23,7 @@ The dispatcher XDP program contains the main function containing the dispatcher
 logic, 10 stub functions that can be replaced by component BPF programs, and a
 configuration structure that is used by the dispatcher logic.
 
-In =libxdp=, this dispatcher is generated by [[https://github.com/xdp-project/xdp-tools/blob/master/lib/libxdp/xdp-dispatcher.c.in][an M4 macro file]] which expands to
+In =libxdp=, this dispatcher is generated by [[https://github.com/xdp-project/xdp-tools/blob/main/lib/libxdp/xdp-dispatcher.c.in][an M4 macro file]] which expands to
 the following:
 
 #+begin_src C
@@ -256,7 +256,7 @@ Having loaded the dispatcher program, =libxdp= then loads each of the component
 programs. To do this, first the list of component programs is sorted by their
 run priority, forming the final run sequence. Should several programs have the
 same run priority, ties are broken in the following arbitrary, but
-deterministic, order (see =cmp_xdp_programs()= [[https://github.com/xdp-project/xdp-tools/blob/master/lib/libxdp/libxdp.c][in libxdp.c]]):
+deterministic, order (see =cmp_xdp_programs()= [[https://github.com/xdp-project/xdp-tools/blob/main/lib/libxdp/libxdp.c][in libxdp.c]]):
 
 - By XDP function name (=bpf_program__name()= from libbpf)
 - By sorting already-loaded programs before not-yet-loaded ones