Miscellaneous formatting and wording tweaks

CONTRIBUTING

@@ -63,7 +63,7 @@ Whenever a branch is ready for publication, a tag will be placed of the
 form v9_X_Y. The 9.12.0 release, for instance, is tagged as v9_12_0.
 
 The branch in which the next major release is being developed is called
-master.
+main.
 
 Reporting bugs
 
@@ -95,15 +95,15 @@ Do not discuss undisclosed security vulnerabilities on any public mailing
 list. ISC has a long history of handling reported vulnerabilities promptly
 and effectively and we respect and acknowledge responsible reporters.
 
-ISC's Security Vulnerability Disclosure Policy is documented at https://
-kb.isc.org/article/AA-00861/0.
+ISC's Security Vulnerability Disclosure Policy is documented at
+https://kb.isc.org/docs/aa-00861.
 
 If you have a crash, you may want to consult ‘What to do if your BIND or
 DHCP server has crashed.’
 
 Contributing code
 
-BIND is licensed under the Mozilla Public License 2.0. Earier versions
+BIND is licensed under the Mozilla Public License 2.0. Earlier versions
 (BIND 9.10 and earlier) were licensed under the ISC License
 
 ISC does not require an explicit copyright assignment for patch
@@ -119,7 +119,7 @@ Patches for BIND may be submitted directly via merge requests in ISC's
 Gitlab source repository for BIND.
 
 Patches can also be submitted as diffs against a specific version of BIND
--- preferably the current top of the master branch. Diffs may be generated
+-- preferably the current top of the main branch. Diffs may be generated
 using either git format-patch or git diff.
 
 Those wanting to write code for BIND may be interested in the developer

CONTRIBUTING.md

@@ -72,7 +72,7 @@ Whenever a branch is ready for publication, a tag will be placed of the
 form `v9_X_Y`.  The 9.12.0 release, for instance, is tagged as `v9_12_0`.
 
 The branch in which the next major release is being developed is called
-`master`.
+`main`.
 
 ### <a name="bugs"></a>Reporting bugs
 
@@ -92,6 +92,7 @@ use credentials from an existing account at GitHub, GitLab, Google,
 Twitter, or Facebook.
 
 ### Reporting possible security issues
+
 If you think you may be seeing a potential security vulnerability in BIND
 (for example, a crash with REQUIRE, INSIST, or ASSERT failure), please
 report it immediately by emailing to security-officer@isc.org. Plain-text
@@ -103,7 +104,8 @@ Do not discuss undisclosed security vulnerabilities on any public mailing list.
 ISC has a long history of handling reported vulnerabilities promptly and
 effectively and we respect and acknowledge responsible reporters.
 
-ISC's Security Vulnerability Disclosure Policy is documented at [https://kb.isc.org/article/AA-00861/0](https://kb.isc.org/article/AA-00861/0).
+ISC's Security Vulnerability Disclosure Policy is documented at
+[https://kb.isc.org/docs/aa-00861](https://kb.isc.org/docs/aa-00861).
 
 If you have a crash, you may want to consult
 [‘What to do if your BIND or DHCP server has crashed.’](https://kb.isc.org/article/AA-00340/89/What-to-do-if-your-BIND-or-DHCP-server-has-crashed.html)
@@ -112,7 +114,8 @@ If you have a crash, you may want to consult
 
 BIND is licensed under the
 [Mozilla Public License 2.0](http://www.isc.org/downloads/software-support-policy/isc-license/).
-Earier versions (BIND 9.10 and earlier) were licensed under the [ISC License](http://www.isc.org/downloads/software-support-policy/isc-license/)
+Earlier versions (BIND 9.10 and earlier) were licensed under the
+[ISC License](https://www.isc.org/licenses/)
 
 ISC does not require an explicit copyright assignment for patch
 contributions.  However, by submitting a patch to ISC, you implicitly
@@ -128,7 +131,7 @@ Patches for BIND may be submitted directly via merge requests in
 repository for BIND.
 
 Patches can also be submitted as diffs against a specific version of
-BIND -- preferably the current top of the `master` branch.  Diffs may
+BIND -- preferably the current top of the `main` branch.  Diffs may
 be generated using either `git format-patch` or `git diff`.
 
 Those wanting to write code for BIND may be interested in the