Documentation: Update to refer to main repository.

Recently OVS adopted a policy of using the inclusive naming word list v1
[1, 2].

This patch addresses the use of the term master repository by
using the term main repository instead.

This is as distinct from the master branch, which remains as a follow-up task.

[1] df5e5cf ("Documentation: Add section on inclusive language.")
[2] https://inclusivenaming.org/word-lists/

Signed-off-by: Simon Horman <horms@ovn.org>

Documentation/internals/committer-grant-revocation.rst

@@ -26,7 +26,7 @@ OVS Committer Grant/Revocation Policy
 =====================================
 
 An OVS committer is a participant in the project with the ability to commit
-code directly to the master repository. Commit access grants a broad ability to
+code directly to the main repository. Commit access grants a broad ability to
 affect the progress of the project as presented by its most important artifact,
 the code and related resources that produce working binaries of Open vSwitch.
 As such it represents a significant level of trust in an individual's

Documentation/intro/install/dpdk.rst

@@ -33,7 +33,7 @@ userspace.
 
     The :doc:`releases FAQ </faq/releases>` lists support for the required
     versions of DPDK for each version of Open vSwitch. If building OVS and
-    DPDK outside of the master build tree users should consult this list
+    DPDK outside of the main build tree users should consult this list
     first.
 
 Build requirements