add note to use npm run clean to troubleshoot (#1073)

Author: evans

packages/apollo/README.md

@@ -96,11 +96,11 @@ ARGUMENTS
   OUTPUT
       Directory to which generated files will be written.
       - For TypeScript/Flow generators, this specifies a directory relative to each source file by default.
-      - For TypeScript/Flow generators with the "outputFlat" flag is set, and for the Swift generator, this specifies a 
+      - For TypeScript/Flow generators with the "outputFlat" flag is set, and for the Swift generator, this specifies a
       file or directory (absolute or relative to the current working directory) to which:
          - a file will be written for each query (if "output" is a directory)
          - all generated types will be written
-      - For all other types, this defines a file (absolute or relative to the current working directory) to which all 
+      - For all other types, this defines a file (absolute or relative to the current working directory) to which all
       generated types are written.
 
 OPTIONS
@@ -308,15 +308,15 @@ DESCRIPTION
 
   Installation of a user-installed plugin will override a core plugin.
 
-  e.g. If you have a core plugin that has a 'hello' command, installing a user-installed plugin with a 'hello' command 
-  will override the core plugin implementation. This is useful if a user needs to update core plugin functionality in 
+  e.g. If you have a core plugin that has a 'hello' command, installing a user-installed plugin with a 'hello' command
+  will override the core plugin implementation. This is useful if a user needs to update core plugin functionality in
   the CLI without the need to patch and update the whole CLI.
 
 ALIASES
   $ apollo plugins:add
 
 EXAMPLES
-  $ apollo plugins:install myplugin 
+  $ apollo plugins:install myplugin
   $ apollo plugins:install https://github.com/someuser/someplugin
   $ apollo plugins:install someuser/someplugin
 ```
@@ -341,7 +341,7 @@ OPTIONS
 DESCRIPTION
   Installation of a linked plugin will override a user-installed or core plugin.
 
-  e.g. If you have a user-installed or core plugin that has a 'hello' command, installing a linked plugin with a 'hello' 
+  e.g. If you have a user-installed or core plugin that has a 'hello' command, installing a linked plugin with a 'hello'
   command will override the user-installed or core plugin implementation. This is useful for development work.
 
 EXAMPLE
@@ -612,6 +612,8 @@ npm test
 
 You can also run `npm` commands within package folders after you have bootstrapped the repository (part of `npm install`).
 
+> Note: if you have issues, try `npm run clean && npm i` to get a fresh install of the packages. Occasionally problems arise when removed dependencies stay around
+
 ## Nock tests
 
 To display the debugging messages for nock, run the following command: