Add sourcegraph links to readme and contributing guide

.github/CONTRIBUTING.md

@@ -23,13 +23,13 @@ Other menu items:
 
 ### Contributing code
 
-You can have a direct impact on the project by helping with its code. To contribute code to Caddy, open a [pull request](https://github.com/mholt/caddy/pulls) (PR). If you're new to our community, that's okay: **we gladly welcome pull requests from anyone, regardless of your native language or coding experience.**
+You can have a direct impact on the project by helping with its code. To contribute code to Caddy, open a [pull request](https://github.com/mholt/caddy/pulls) (PR). If you're new to our community, that's okay: **we gladly welcome pull requests from anyone, regardless of your native language or coding experience.** You can get familiar with Caddy's code base by using [code search at Sourcegraph](https://sourcegraph.com/github.com/mholt/caddy/-/search).
 
 We hold contributions to a high standard for quality :bowtie:, so don't be surprised if we ask for revisions—even if it seems small or insignificant. Please don't take it personally. :wink: If your change is on the right track, we can guide you to make it mergable.
 
 Here are some of the expectations we have of contributors:
 
-- If your change is more than just a minor alteration, **open an issue to propose your change first.** This way we can avoid confusion, coordinate what everyone is working on, and ensure that changes are in-line with the project's goals and the best interests of its users. If there's already an issue about it, you can comment on the existing one to claim it.
+- If your change is more than just a minor alteration, **open an issue to propose your change first.** This way we can avoid confusion, coordinate what everyone is working on, and ensure that changes are in-line with the project's goals and the best interests of its users. If there's already an issue about it, comment on the existing issue to claim it.
 
 - **Keep pull requests small.** Smaller PRs are more likely to be merged because they are easier to review! We might ask you to break up large PRs into smaller ones. [An example of what we DON'T do.](https://twitter.com/iamdevloper/status/397664295875805184)
 
@@ -41,7 +41,7 @@ Here are some of the expectations we have of contributors:
 
 - **[Squash](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html) insignificant commits.** Every commit should be significant. Commits which merely rewrite a comment or fix a typo can be combined into another commit that has more substance. Interactive rebase can do this, or a simpler way is `git reset --soft <diverging-commit>` then `git commit -s`.
 
-- **Own your contributions.** Caddy is a growing project, and it's much better when individual contributors can help maintain their change after it is merged.
+- **Own your contributions.** Caddy is a growing project, and it's much better when individual contributors help maintain their change after it is merged.
 
 - **Use comments properly.** We expect good godoc comments for package-level functions, types, and values. Comments are also useful whenever the purpose for a line of code is not obvious.
 

README.md

@@ -128,9 +128,9 @@ If you have questions or concerns about Caddy' underlying crypto implementations
 
 ## Contributing
 
-**[Join our forum](https://caddy.community) where you can chat with other Caddy users and developers!**
+**[Join our forum](https://caddy.community) where you can chat with other Caddy users and developers!** To get familiar with the code base, try [Caddy code search on Sourcegraph](https://sourcegraph.com/github.com/mholt/caddy/-/search)!
 
-Please see our [contributing guidelines](https://github.com/mholt/caddy/blob/master/.github/CONTRIBUTING.md). If you want to write a plugin, check out the [developer wiki](https://github.com/mholt/caddy/wiki).
+Please see our [contributing guidelines](https://github.com/mholt/caddy/blob/master/.github/CONTRIBUTING.md) for instructions. If you want to write a plugin, check out the [developer wiki](https://github.com/mholt/caddy/wiki).
 
 We use GitHub issues and pull requests only for discussing bug reports and the development of specific changes. We welcome all other topics on the [forum](https://caddy.community)!