docs: update contribution checklist

- Update Go version 1.11 to 1.12
- Fix broken link in GitHub PR template
- Fix inconsistent number of spaces after checkbox
- Add proper link to "Ideal Git Commit structure"

.github/pull_request_template.md

@@ -2,24 +2,23 @@
 
 - [ ] If this is your first time contributing, we recommend you read the [Code
   Contribution Guidelines](https://github.com/lightningnetwork/lnd/blob/master/docs/code_contribution_guidelines.md)
-- [ ] All changes are Go version 1.11 compliant
-- [ ]  The code being submitted is commented according to the
-  [Code Documentation and Commenting](#CodeDocumentation) section
-- [ ]  For new code: Code is accompanied by tests which exercise both
+- [ ] All changes are Go version 1.12 compliant
+- [ ] The code being submitted is commented according to [Code Documentation and Commenting](https://github.com/lightningnetwork/lnd/blob/master/docs/code_contribution_guidelines.md#CodeDocumentation)
+- [ ] For new code: Code is accompanied by tests which exercise both
   the positive and negative (error paths) conditions (if applicable)
-- [ ]  For bug fixes: Code is accompanied by new tests which trigger
+- [ ] For bug fixes: Code is accompanied by new tests which trigger
   the bug being fixed to prevent regressions
-- [ ]  Any new logging statements use an appropriate subsystem and
+- [ ] Any new logging statements use an appropriate subsystem and
   logging level
-- [ ]  Code has been formatted with `go fmt`
-- [ ]  For code and documentation: lines are wrapped at 80 characters
+- [ ] Code has been formatted with `go fmt`
+- [ ] For code and documentation: lines are wrapped at 80 characters
   (the tab character should be counted as 8 characters, not 4, as some IDEs do
   per default)
-- [ ]  Running `make check` does not fail any tests
-- [ ]  Running `go vet` does not report any issues
-- [ ]  Running `make lint` does not report any **new** issues that did not
+- [ ] Running `make check` does not fail any tests
+- [ ] Running `go vet` does not report any issues
+- [ ] Running `make lint` does not report any **new** issues that did not
   already exist
 - [ ] All commits build properly and pass tests. Only in exceptional
   cases it can be justifiable to violate this condition. In that case, the
   reason should be stated in the commit message.
-- [ ] Commits have a logical structure ([see section 4.5, of the Code Contribution Guidelines])
+- [ ] Commits have a logical structure according to [Ideal Git Commit Structure](https://github.com/lightningnetwork/lnd/blob/master/docs/code_contribution_guidelines.md#IdealGitCommitStructure)

docs/code_contribution_guidelines.md

@@ -612,9 +612,8 @@ Rejoice as you will now be listed as a [contributor](https://github.com/lightnin
 
 #### 6.1. Contribution Checklist
 
-- [  ] All changes are Go version 1.11 compliant
-- [  ] The code being submitted is commented according to the
-  [Code Documentation and Commenting](#CodeDocumentation) section
+- [  ] All changes are Go version 1.12 compliant
+- [  ] The code being submitted is commented according to [Code Documentation and Commenting](#CodeDocumentation)
 - [  ] For new code: Code is accompanied by tests which exercise both
   the positive and negative (error paths) conditions (if applicable)
 - [  ] For bug fixes: Code is accompanied by new tests which trigger
@@ -632,7 +631,7 @@ Rejoice as you will now be listed as a [contributor](https://github.com/lightnin
 - [  ] All commits build properly and pass tests. Only in exceptional
   cases it can be justifiable to violate this condition. In that case, the
   reason should be stated in the commit message.
-- [  ] Commits have a logical structure (see section 4.5).
+- [  ] Commits have a logical structure according to [Ideal Git Commit Structure](#IdealGitCommitStructure).
 
 <a name="Licensing" />