Add help details for configuration documentation of collectCoverageFrom

Due to breaking changes in an upgrade of the dependency micromatch
from ^2.3.11 to ^3.1.10 many users saw their coverage reporting
failing because their glob matching was in an unsupported format.

Adding the help text here gives users a good starting point for
debugging when they run into issues concerning this option. This should
help alleviate support issues created concerning this configuration
option.

Issue jestjs#6563 is a good example of what could be avoided in the future
with this addition to the documentation.

docs/Configuration.md

@@ -153,6 +153,23 @@ This will collect coverage information for all the files inside the project's `r
 
 _Note: This option requires `collectCoverage` to be set to true or Jest to be invoked with `--coverage`._
 
+<details>
+ <summary>Help:</summary>
+ If you are seeing coverage output such as...
+
+ ```
+ =============================== Coverage summary ===============================
+ Statements : Unknown% ( 0/0 )
+ Branches : Unknown% ( 0/0 )
+ Functions : Unknown% ( 0/0 )
+ Lines : Unknown% ( 0/0 )
+ ================================================================================
+ Jest: Coverage data for global was not found.
+ ```
+
+ Most likely your glob patterns are not matching any files. Refer to the [micromatch](https://github.com/jonschlinkert/micromatch) documentation to ensure your globs are compatible.
+</details>
+
 ### `coverageDirectory` [string]
 
 Default: `undefined`