Replace references to bazel-genfiles with bazel-bin

In bazel 0.25 the target directory was changed from bazel-genfiles
to bazel-bin and bazel-genfiles was symlinked to bazel-bin.

In bazel 1.0 the symlink no longer gets created, and this causes the
./tools/maven/api.sh script to fail on a clean workspace because it
still refers to the old location:

  ./tools/maven/api.sh: line 66:
  ./bazel-genfiles/tools/maven/api_install.sh: No such file or directory

Fix api.sh to use bazel-bin, and also update dev-build-plugin.txt to
refer to bazel-bin.

Note that some documentation was previously updated in I9521cd7e5.

Bug: Issue 11757
Change-Id: I21f204d44ac78559f51ad2e62b085240170d83a7
diff --git a/Documentation/dev-build-plugins.txt b/Documentation/dev-build-plugins.txt
index 072c22c..9bf41e2 100644
--- a/Documentation/dev-build-plugins.txt
+++ b/Documentation/dev-build-plugins.txt
@@ -69,7 +69,7 @@
 The output can be normally found in the following directory:
 
 ----
-bazel-genfiles/plugins/<plugin-name>/<plugin-name>.jar
+bazel-bin/plugins/<plugin-name>/<plugin-name>.jar
 ----
 
 Some plugins describe their build process in `src/main/resources/Documentation/build.md`
diff --git a/tools/maven/api.sh b/tools/maven/api.sh
index e72e3cb..076ef87 100755
--- a/tools/maven/api.sh
+++ b/tools/maven/api.sh
@@ -63,4 +63,4 @@
 bazel build //tools/maven:gen_${command} "$@" || \
   { echo "bazel failed to build gen_${command}. Use VERBOSE=1 for more info" ; exit 1 ; }
 
-./bazel-genfiles/tools/maven/${command}.sh
+./bazel-bin/tools/maven/${command}.sh