add documentation for context methods

Author: abhinavmehndiratta

src/Context_Methods.jl

@@ -1,17 +1,59 @@
 import Printf.@printf
 
+"""
+    GrB_init(mode)
+
+GrB_init must called before any other GraphBLAS operation.
+GrB_init defines the mode that GraphBLAS will use: blocking or non-blocking.
+With blocking mode, all operations finish before returning to the user application.
+With non-blocking mode, operations can be left pending, and are computed only when needed.
+"""
 function GrB_init(mode::GrB_Mode)
     return GrB_Info(ccall(dlsym(graphblas_lib, "GrB_init"), Cint, (Cint, ), mode))
 end
 
+"""
+    GrB_wait()
+
+GrB_wait forces all pending operations to complete.
+Blocking mode is as if GrB_wait is called whenever a GraphBLAS method or operation returns to the user.
+"""
 function GrB_wait()
     return GrB_Info(ccall(dlsym(graphblas_lib, "GrB_wait"), Cint, (), ))
 end
 
+"""
+    GrB_finalize()
+
+GrB_finalize must be called as the last GraphBLAS operation.
+GrB_finalize does not call GrB_wait; any pending computations are abandoned.
+"""
 function GrB_finalize()
     return GrB_Info(ccall(dlsym(graphblas_lib, "GrB_finalize"), Cint, (), ))
 end
 
+"""
+    GrB_error()
+
+Each GraphBLAS method and operation returns a GrB_Info error code.
+GrB_error returns additional information on the error.
+
+# Examples
+```jldoctest
+julia> using SuiteSparseGraphBLAS
+
+julia> GrB_init(GrB_NONBLOCKING)
+GrB_SUCCESS::GrB_Info = 0
+
+julia> GrB_init(GrB_NONBLOCKING)
+GrB_INVALID_VALUE::GrB_Info = 5
+
+julia> GrB_error()
+GraphBLAS error: GrB_INVALID_VALUE
+function: GrB_init (mode)
+GrB_init must not be called twice
+```
+"""
 function GrB_error()
     @printf("%s", unsafe_string(ccall(dlsym(graphblas_lib, "GrB_error"), Cstring, (), )))
 end