Add notice in README pointing to sourcegraph/zoekt

Change-Id: I132d0b816c337be8ee7b1ded6087c9d6b8469efd

CONTRIBUTING

@@ -1,46 +1,4 @@
-
-Before sending a patch, please fill out a Google CLA,
-using the following form:
-
-  https://cla.developers.google.com/clas
-
-For submitting patches, please use gerrit:
-
-* Make sure all tests pass:
-
-    go test github.com/google/zoekt/...
-
-* Add the following to your .git/config:
-
-    [remote "gerrit"]
-            url = https://gerrit.googlesource.com/zoekt
-            fetch = +refs/heads/*:refs/remotes/origin/*
-
-* Create an account at https://gerrit-review.googlesource.com/
-  and follow `Settings -> HTTP Credentials -> Obtain password`
-
-* Add a Change ID to the bottom of your commit message: run the following,
-  and append its output to your commmit message
-
-    echo "Change-Id: I"$(head -c 20 /dev/urandom | sha1sum | awk '{print $1}')
-
-  Or install the hook:
-
-    curl -Lo .git/hooks/commit-msg https://gerrit-review.googlesource.com/tools/hooks/commit-msg
-    chmod +x .git/hooks/commit-msg
-
-* Upload to gerrit:
-
-    git push gerrit HEAD:refs/for/master
-
-* Add [email protected] as a reviewer in the Web UI
-
-* To make changes in response to the review, do
-
-    git commit --amend
-
-  and include your updated files into the commit. Then
-
-    git push gerrit HEAD:refs/for/master
-
-  will push a new patchset.
+**NOTICE:**
+[github.com/sourcegraph/zoekt](https://github.com/sourcegraph/zoekt) is the
+active main repository for Zoekt development. Please contribute pull requests
+to that repository.

README.md

@@ -6,6 +6,8 @@
 This is a fast text search engine, intended for use with source
 code. (Pronunciation: roughly as you would pronounce "zooked" in English)
 
+**NOTICE:** [github.com/sourcegraph/zoekt](https://github.com/sourcegraph/zoekt) is the active main repository for Zoekt development.
+
 INSTRUCTIONS
 ============