Update documentation for InlineModel features.

[jacobhegna]

Change caller -> callee in the last feature.

[mtrofin]

LGTM, thanks!

llvm/include/llvm/Analysis/InlineModelFeatureMaps.h

#define INLINE_FEATURE_ITERATOR(M)                                             \
   M(CallSiteHeight, "callsite_height",                                         \
     "position of the call site in the original call graph - measured from "    \
     "the farthest SCC")                                                        \
   M(NodeCount, "node_count",                                                   \
     "total current number of defined functions in the module")                 \
   M(NrCtantParams, "nr_ctant_params",                                          \
     "number of parameters in the call site that are constants")                \
   M(CostEstimate, "cost_estimate", "total cost estimate (threshold - free)")   \
-  M(EdgeCount, "edge_count",                                                   \
+  M(EdgeCount, "edge_count", "total number of calls in the module")            \
+  M(CallerUsers, "caller_users",                                               \
     "number of module-internal users of the caller, +1 if the caller is "      \
     "exposed externally")                                                      \
-  M(CallerUsers, "caller_users",                                               \
-    "number of blocks reached from a conditional instruction, in the caller")  \
   M(CallerConditionallyExecutedBlocks, "caller_conditionally_executed_blocks", \
     "number of blocks reached from a conditional instruction, in the caller")  \
   M(CallerBasicBlockCount, "caller_basic_block_count",                         \
     "number of basic blocks in the caller")                                    \
   M(CalleeConditionallyExecutedBlocks, "callee_conditionally_executed_blocks", \
     "number of blocks reached from a conditional instruction, in the callee")  \
   M(CalleeUsers, "callee_users",                                               \
-    "number of blocks reached from a conditional instruction, in the callee")
+    "number of module-internal users of the callee, +1 if the callee is "      \
+    "exposed externally")
 
 enum class FeatureIndex : size_t {
 #define POPULATE_INDICES(INDEX_NAME, NAME, COMMENT) INDEX_NAME,
   INLINE_FEATURE_ITERATOR(POPULATE_INDICES)
 #undef POPULATE_INDICES
       NumberOfFeatures
 };